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Russian Journal of Bioorganic Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of Coordination Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of General Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of Inorganic Chemistry     Hybrid Journal  
Sainstek : Jurnal Sains dan Teknologi     Open Access  
Science China Chemistry     Hybrid Journal   (Followers: 2)
Science Talks     Full-text available via subscription   (Followers: 3)
Sciences & Technologie A : sciences exactes     Open Access  
Scientific Journal of Frontier Chemical Development     Open Access   (Followers: 2)
Scientific Reports     Open Access   (Followers: 92)
Sensors and Actuators B: Chemical     Hybrid Journal   (Followers: 18)
Sensors and Actuators Reports     Open Access   (Followers: 7)
Separation & Purification Reviews     Hybrid Journal   (Followers: 7)
Separation Science and Technology     Hybrid Journal   (Followers: 12)
Separations     Open Access   (Followers: 5)
Silicon Chemistry     Hybrid Journal   (Followers: 1)
Small Methods     Hybrid Journal   (Followers: 1)
Small Science     Open Access  
Small Structures     Hybrid Journal   (Followers: 2)
Smart Materials Research     Open Access   (Followers: 7)
SmartMat     Open Access   (Followers: 1)
Soft     Open Access  
Soft Nanoscience Letters     Open Access   (Followers: 1)
Solar RRL     Hybrid Journal  
Solid State Communications     Hybrid Journal   (Followers: 7)
Solid State Nuclear Magnetic Resonance     Hybrid Journal   (Followers: 3)
Solid State Sciences     Hybrid Journal   (Followers: 7)
Solvent Extraction and Ion Exchange     Hybrid Journal   (Followers: 7)
SPE Polymers     Open Access   (Followers: 1)
Spectral Analysis Review     Open Access  
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy     Hybrid Journal   (Followers: 15)
Spectrochimica Acta Part B: Atomic Spectroscopy     Hybrid Journal   (Followers: 17)
Spectroscopy and Spectral Analysis     Full-text available via subscription   (Followers: 1)
Starch / Staerke     Hybrid Journal   (Followers: 3)
Steel Research International     Hybrid Journal   (Followers: 23)
Structural Chemistry     Hybrid Journal   (Followers: 1)
Substantia     Open Access  
Supramolecular Chemistry     Hybrid Journal   (Followers: 5)
Supramolecular Materials     Full-text available via subscription   (Followers: 4)
Surface and Coatings Technology     Hybrid Journal   (Followers: 32)
Surface Science     Hybrid Journal   (Followers: 21)
Surface Science Reports     Full-text available via subscription   (Followers: 13)
Surfaces     Open Access   (Followers: 2)
Surfaces and Interfaces     Hybrid Journal   (Followers: 1)
Sustainable Chemical Processes     Open Access   (Followers: 4)
Sustainable Chemistry and Pharmacy     Full-text available via subscription   (Followers: 1)
Synfacts     Hybrid Journal   (Followers: 5)
Synlett     Hybrid Journal   (Followers: 43)
Synthesis     Hybrid Journal   (Followers: 53)
Talanta     Hybrid Journal   (Followers: 10)
Talanta Open     Full-text available via subscription   (Followers: 4)
Tecnología Química     Open Access  
Telematics and Informatics Reports     Full-text available via subscription   (Followers: 4)
Tenside Surfactants Detergents     Full-text available via subscription   (Followers: 1)
Tetrahedron     Hybrid Journal   (Followers: 88)
Tetrahedron Chem     Full-text available via subscription   (Followers: 1)
Tetrahedron Letters     Hybrid Journal   (Followers: 90)
The Alkaloids: Chemistry and Biology     Full-text available via subscription   (Followers: 1)
The All Results Journals : Chem     Open Access   (Followers: 1)
The Canadian Journal of Chemical Engineering     Hybrid Journal   (Followers: 5)
The Enzymes     Full-text available via subscription   (Followers: 2)
The Protein Journal     Hybrid Journal   (Followers: 5)
Theoretical and Experimental Chemistry     Hybrid Journal  
Theoretical Chemistry Accounts     Hybrid Journal   (Followers: 6)
Thermochimica Acta     Hybrid Journal   (Followers: 18)
Tip Revista Especializada en Ciencias Quimico-Biologicas     Open Access  
Topics in Current Chemistry     Hybrid Journal  
Toxicology International     Full-text available via subscription   (Followers: 5)
Toxicology Research     Partially Free   (Followers: 9)
Transition Metal Chemistry     Hybrid Journal   (Followers: 6)
Trends in Chemistry     Hybrid Journal   (Followers: 2)
Turkish Computational and Theoretical Chemistry     Open Access  
Ultrasonics Sonochemistry     Hybrid Journal   (Followers: 2)
Universal Journal of Chemistry     Open Access   (Followers: 1)
Vietnam Journal of Chemistry     Hybrid Journal  
Western Undergraduate Research Journal : Health and Natural Sciences     Open Access  
Wiley Interdisciplinary Reviews : Computational Molecular Science     Hybrid Journal   (Followers: 5)
World Journal of Chemical Education     Open Access   (Followers: 2)
X-Ray Spectrometry     Hybrid Journal   (Followers: 4)

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Number of Followers: 5  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2297-8739
Published by MDPI Homepage  [258 journals]
  • Separations, Vol. 10, Pages 461: The Mass Spectrometry Identification,
           Antimicrobial Genes Detection, and Proteomics Analysis of Stutzerimonas
           stutzeri Strain Was Isolated from Industrial Wastewater

    • Authors: Zongwu Wang, Xiaoyan Sun, Xing Chen, Haifeng Wang, Hongxuan He
      First page: 461
      Abstract: A large amount of organic matter, heavy metals, and even antibiotics are present in industrial wastewater, aquaculture waters, and various types of sewage, along with abundant microorganisms. To date, only a few studies involving the resistance and proteomics of Stutzerimonas stutzeri in high-salt wastewater are available. Herein, a comprehensive assessment of a newly isolated Stutzerimonas stutzeri strain, which is present in high-salt wastewater, was performed using mass spectrometry, genetic identification, and biochemical analysis to characterize the genetic and biochemical properties. Growth experiments revealed that the Stutzerimonas stutzeri strain had a moderate growth rate in nutrient broth, and the bacterial count was not high. Further analysis highlighted an apparent susceptibility of this strain to most antibiotics but some resistance to chloramphenicol and minocycline. A resistance gene assay results showed that the gene gyrB was associated with antibiotic resistance in this Stutzerimonas stutzeri strain. Proteomic analysis revealed for the first time the co-existence of two drug-resistance-related proteins (Multidrug/solvent RND membrane fusion protein and MexE) in Stutzerimonas stutzeri. Moreover, Stutzerimonas stutzeri isolated from high-salt wastewater was subjected to drug resistance gene detection, and the total protein of Stutzerimonas stutzeri was detected by protein mass spectrometry analysis. The subcellular classification shows that the 50 proteins with the highest abundance are divided into cell inner membrane, cell outer membrane, cytoplasm, cytoplasmic side, membrane, multi-pass membrane protein, and peripheral membrane protein, among which the proportion of cytoplasmic components is the highest. Overall, this study’s findings provide a new perspective for further research on the characteristics of Stutzerimonas stutzeri in high-salt wastewater.
      Citation: Separations
      PubDate: 2023-08-22
      DOI: 10.3390/separations10090461
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 462: Morphology of Particulate Structures on a

    • Authors: Lukas Poggemann, Benedikt King, Jörg Meyer, Achim Dittler
      First page: 462
      Abstract: Fundamental microscopic investigations are based on the interaction between filter fiber and particles. The fibrous filter theory is based on a single fiber of a fiber array, and experiments focus either on a single fiber or a fiber array. This study investigates the particle loading process of a fiber array and focuses on the microscopic development of particle structures on the fiber array. Gravimetric measurements and image analysis of the array were used to study the development of the particle structure and morphology. Microscopic analysis of the video data focused on the evolution of particle accumulation within the fiber spacing, the development of boundary lines of the particle structure, and the number/size of bridges and pores within the particle structure. For the tested flow velocities, an increase in mass was observed to increase the duration of the filtration process. An extreme increase in deposited mass was observed at the moment of complete blocking (clogging) of the fiber spacing at flow velocities of 0.65 m/s. The size of pores (hydraulic diameter) increased with the flow velocity during the loading procedure. However, the total number of pores was higher in tests with lower Stokes numbers due to the dendritic and more porous structure. This work provides insights into the growth kinetics and structural setup of the particle structure (on a microscopic level). This will improve the understanding of the change of the filtration process from the transition phase to the clogging phase in fibrous filters.
      Citation: Separations
      PubDate: 2023-08-23
      DOI: 10.3390/separations10090462
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 463: Effective Removal of Hexavalent Chromium
           from Aqueous Solutions Using Quaternary Ammonium-Functionalized Magnetic
           Graphene Oxide Composites

    • Authors: Yue Huang, Weibin Huang, Ying Chen, Jianteng Sun, Maofeng Liang, Yonggui Guo, Xiaping Liu, Mingqiang Liu, Yajing Wei, Junfu Wei, Huan Zhang, Huicai Wang
      First page: 463
      Abstract: Novel quaternary ammonium/magnetic graphene oxide composites (M-PAS-GO) that efficiently remove Cr(VI) ions were fabricated through the introduction of the (3-aminopropyl) triethoxysilane and Fe3O4 nanoparticles on the surface of GO, and then modified with n-butyl bromide. The fabricated M-PAS-GO was comprehensively characterized by SEM, TEM, EDX, XRD, Raman spectroscopy and FTIR, and the results manifest that the quaternary ammonium group was introduced onto the surface of GO. Under the reaction conditions of pH 3.20, temperature of 25 °C and M-PAS-GO dosage of 0.01 g/50 mL, 90% of 10 mg/L Cr(VI) ions were removed from the solution within 20 min. The kinetics study indicates that the adsorption process followed the pseudo-second-order model and was surface reaction-controlled. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggest that the adsorption process was an exothermic and spontaneous process. The maximum adsorption capacities of Cr(VI) ions on M-PAS-GO composites calculated by the Langmuir model were 46.48 mg/g. Moreover, the reusability and stability of M-PAS-GO demonstrates its economic sustainability. This study suggests that M-PAS-GO is a potential candidate adsorbent for the separation of Cr(VI) from wastewater.
      Citation: Separations
      PubDate: 2023-08-24
      DOI: 10.3390/separations10090463
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 464: Potential Use of Agricultural
           Waste—Carob Kibbles (Ceratonia siliqua L.) as a Biosorbent for
           Removing Boron from Wastewater

    • Authors: Luz Adriana Díaz, Jorge Dias Carlier, Izabela Michalak, María Clara Costa
      First page: 464
      Abstract: The release of boron into the environment as a result of anthropogenic activity modifies sustainable natural conditions, thus affecting ecosystems. To meet water quality regulations, commercial and natural boron adsorbents are available to reduce its concentrations in industrial effluents, with the former being not only more expensive but also less sustainable. In the publication, the biosorption parameters of carob kibbles (Ceratonia siliqua L.) were optimized in order to remove boron from aqueous solutions using batch experiments. The biosorbent used in the present research was agro-waste biomass provided by the local locust-beam gum industry. Boron removal by carob kibbles was favored at high initial pH values, and this capacity was found to be a function of boron initial concentration, biosorbent content in the solution, and particle size. The change in temperature did not affect the potential of biomass to remove boron. The highest boron removal efficiency (55.1%) was achieved under the following optimal conditions: 50 g/L biosorbent dose (Cs), with particle size range 0.025–0.106 mm, for the initial concentration (C0) of boron in the solution of 100 mg/L, at an initial pH of 11.5, for 5 h at 25 °C. This investigation suggests that carob kibble agro-waste can be valorized as a biosorbent to remove boron from wastewater, and the boron-loaded residue may eventually be explored as a new boron-fertilizer.
      Citation: Separations
      PubDate: 2023-08-24
      DOI: 10.3390/separations10090464
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 465: Carob Pulp Flour Extract Obtained by a
           Microwave-Assisted Extraction Technique: A Prospective Antioxidant and
           Antimicrobial Agent

    • Authors: Jana Zahorec, Dragana Šoronja-Simović, Sunčica Kocić-Tanackov, Sandra Bulut, Nikola Martić, Katarina Bijelić, Danica Božović, Branimir Pavlić
      First page: 465
      Abstract: In this study, carob pulp flour (CF) extract was characterized as a high-value antioxidant and antimicrobial agent. CF extracts were obtained using microwave-assisted extraction (MAE) and optimization of the MAE process was accomplished using response surface methodology. The studied processing parameters of MAE were the liquid/solid (L/S) ratio (10–30 mL/g), extraction time (15–35 min), and ethanol concentration (40–80% w/w). The efficiency of the extraction of valuable compounds from CF was evaluated by the determining extraction yield (Y), total phenolic(TP), total flavonoid (TF) content, and antioxidant activity (DPPH, FRAP, and ABTS). The optimized MAE parameters for maximizing the yields of target compounds and antioxidant activity were the L/S ratio 30 mL/g, extraction time 35 min, and ethanol concentration 40%. The experimentally obtained values for TP, TF, DPPH, FRAP, and ABTS were 1609.92 GAE/100 g, 271.92 CE/100 g, 99.02 µMTE/g, 50.45 µM Fe2+/g, and 110.55 µMTE/g, respectively. The optimized CF extract was compared with the CF extracts obtained by conventional solid–liquid extraction (S/L) and ultrasound-assisted extraction (UAE) and was found to be more beneficial due to a 30% higher yield of TP and TF and 30–80% higher antioxidant activity. The phenolic profiles of the three extracts were quite similar. The microdilution method confirmed the antibacterial activity of MAE and S/L extracts while the antifungal effect was not observed.
      Citation: Separations
      PubDate: 2023-08-24
      DOI: 10.3390/separations10090465
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 466: Green Synthesis of Zinc Oxide
           Nanoparticles Using Aqueous Extracts of Hibiscus cannabinus L.: Wastewater
           Purification and Antibacterial Activity

    • Authors: Xitao Yang, Xuan Cao, Chenxiao Chen, Liping Liao, Sitian Yuan, Siqi Huang
      First page: 466
      Abstract: The green preparation of metal oxide nanoparticles is an environmentally friendly method, which could reduce the use of toxic solvents and their impact on the environment. The purpose of this study is to investigate the green synthesis of zinc oxide (ZnO) nanoparticles using extracts of Hibiscus cannabinus leaves and to evaluate their potential applications in environmental remediation. In this work, ZnO nanoparticles were successfully prepared and thoroughly characterized using UV–vis, Fourier transform infrared analysis (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM) analysis, and scanning electron microscope (SEM) with energy dispersive x-ray analysis (EDAX). As a result, the synthesized ZnO nanoparticles showed a good adsorption capacity for Congo red (CR), and satisfactory antioxidant and antibacterial activities. They exhibited good adsorption and removal abilities for CR in aqueous solutions. With the conditions optimized, the adsorption kinetics and isotherms were fitted to the pseudo-second-order model and the Langmuir model. The ZnO nanoparticles could also effectively scavenge 2-2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-di(3-ethylbenzthiazoline sulphonate) (ABTS) radicals, and appeared to inhibit the growth of Escherichia coli and Staphylococcus aureus bacteria. Based on the identified adsorption capacity, the green synthesized ZnO nanoparticles demonstrated their potential to be used in the removal of dyeing wastewater and in the further purification of water due to their antioxidant activity and antibacterial activity.
      Citation: Separations
      PubDate: 2023-08-24
      DOI: 10.3390/separations10090466
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 467: Fluoride Removal from Water Sources by
           Adsorption on MOFs

    • Authors: Athanasia K. Tolkou, Anastasios I. Zouboulis
      First page: 467
      Abstract: Fluoride is present in several groundwaters due to natural or anthropogenic origins. Although it is necessary for physiological human functions (in small amounts, i.e., 0.5–1.2 mg/L), it could be very harmful when it exceeds the maximum permissible concentration limit of 1.5 mg/L (according to WHO). Among the numerous technologies for removing fluoride from waters, metal–organic framework (MOF) materials are considered to be promising adsorbents due to their advantages of high porosity, high specific surface area, diverse functions and easy modification. In this study, the synthesis of MOFs and the progress of their application to the removal of fluoride from contaminated water, as published in the recent literature mainly over the past five years, are reviewed. The adsorption mechanism(s) and its main characteristics, such as effect of initial fluoride concentration, adsorbent dosage, solution pH, contact time, adsorption capacity, thermodynamic and regeneration studies, etc., for the removal of fluoride with the addition of different MOFs are compared. According to these comparisons, the hydrothermal/solvothermal synthesis method is most commonly used for the preparation of MOFs, whereas higher BET surface areas are shown by specific MOFs based on aluminum metal ions. The main fluoride adsorption mechanisms were found to be electrostatic attraction and/or complexation. The most common pH for conducting experiments was 7.0, but several examined materials were found to be effective over a wide pH range. Four to six regeneration cycles were successfully applied on average, regarding the MOFs under review, whereas in the majority of these cases, the sorption process was found to be endothermic.
      Citation: Separations
      PubDate: 2023-08-24
      DOI: 10.3390/separations10090467
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 468: Adsorption-Based Pretreatment of
           Irrigation Water to Prevent Water Quality Issues

    • Authors: Tamás Kucserka, Gábor István Németh, Ivett Pálfi, Zsolt L. Kiss, Etelka Tombácz, Ildikó Galambos
      First page: 468
      Abstract: Access to and the use of irrigation water of adequate quality and targeted nutrient supplementation have become more widespread in recent years. Both crop quality and the irrigation system lifetime are affected by the quality of the water used for irrigation. Micro-irrigation (e.g., drip and sprinkle) is becoming increasingly common alongside the more typical irrigation methods, but it requires expertise and pre-treatment to ensure a proper water supply. The most significant problem is clogging, which can greatly reduce irrigation efficiency. Treatment for irrigation purposes mainly depends on the contaminants that are present in the water. The main treatment options available are biological, electromagnetic and electrostatic treatments, but these have a wide range of effectiveness levels compared to membrane separation technologies. In addition, adsorption treatments are also available, which, depending on the adsorbent used, can greatly improve the pre-treatment of irrigation water. This work provides an overview of adsorbents suitable for the treatment of irrigation water and their effectiveness. The separation of interfering components via adsorption is effective and promising for future application as the expected irrigation demands increase.
      Citation: Separations
      PubDate: 2023-08-24
      DOI: 10.3390/separations10090468
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 469: Optimization of the Vacuum Fractional
           Distillation Process for Enhancing the α-Guaiene of Patchouli Oil
           with Response Surface Methodology

    • Authors: Asri Widyasanti, Sarifah Nurjanah, Bambang Nurhadi, Che Puteh Osman
      First page: 469
      Abstract: α-guaiene is one of the primary sesquiterpene compounds used as a flavor and fragrance agent in patchouli oil. The fraction of patchouli oil that is rich in α-guaiene has been successfully isolated. In the present work, α-guaiene was isolated from crude patchouli oil through vacuum fractional distillation followed by GC-MS identification. Three important process parameters—feed volume, reflux ratio, and applied run pressure—were investigated and optimized using Box–Behnken design. The research methodology was an experimental laboratory using response surface methodology (RSM) with a feed volume level from 75 mL to 125 mL, a reflux ratio from 10:1 to 30:1, and an applied run pressure from 5 mmHg to 15 mmHg. The α-guaiene-enriched fraction was found in the first distillate fraction patchouli. The optimum condition that generated α-guaiene fraction at 44.70% purity was the treatment with a feed volume of 75 mL, a reflux ratio of 24:1, and applied run pressure of 14.80 mmHg. Results indicated that feed volume did not significantly affect the α-guaiene content, while the applied run pressure and reflux ratio used had a significant effect. A quadratic mathematical model with R2 0.861 and validation 96.14% was suitable for predicting the optimum α-guaiene fraction content during the vacuum fractional distillation process.
      Citation: Separations
      PubDate: 2023-08-25
      DOI: 10.3390/separations10090469
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 470: Isolation of Alkaloids from Sinomenium
           acutum by Centrifugal Partition Chromatography and Their Ameliorating
           Effects on Dexamethasone-Induced Atrophy in C2C12 Myotubes

    • Authors: Eun Ju Jung, Ji Hoon Kim, Hye Mi Kim, Shuo Guo, Do Hyun Lee, Gyu Min Lim, Ahmed Shah Syed, Wondong Kim, Chul Young Kim
      First page: 470
      Abstract: Bioactivity-guided isolation was conducted using centrifugal partition chromatography (CPC) from an extract of Sinomenium acutum rhizome, which has shown promising preventive effects in a dexamethasone-induced C2C12 myotube atrophy model. CPC was operated with a solvent system of n-butanol–acetonitrile–water (10:2:8, v/v/v, containing 0.5% triethylamine) in dual mode (ascending to descending), which provided a high recovery rate (>99%) with a high resolution. Then, the preventive effects of the obtained CPC fractions were examined against dexamethasone-induced atrophy in C2C12 myotubes according to the weight ratios of the obtained fractions. The active fractions were further purified by semi-preparative HPLC that led to obtaining five alkaloids, one lignan glycoside, and one phenylpropanoid glycoside. Among these, at a concentration of 1 nM, sinomenine, magnoflorine, and acutumine could ameliorate dexamethasone-induced myotube atrophy in C2C12 myotubes by 9.3%, 13.8%, and 11.3%, respectively.
      Citation: Separations
      PubDate: 2023-08-25
      DOI: 10.3390/separations10090470
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 471: Exploring the Impact of In Vitro
           Gastrointestinal Digestion in the Bioaccessibility of Phenolic-Rich
           Chestnut Shells: A Preliminary Study

    • Authors: Diana Pinto, Ana Sofia Ferreira, Julián Lozano-Castellón, Emily P. Laveriano-Santos, Rosa M. Lamuela-Raventós, Anna Vallverdú-Queralt, Cristina Delerue-Matos, Francisca Rodrigues
      First page: 471
      Abstract: Chestnut shells (CS), the principal by-product of the chestnut processing industry, contain high concentrations of flavonoids and other polyphenols with huge interest for the nutraceuticals field. Nonetheless, the bioaccessibility and bioactivity of phytochemicals can be influenced by their digestibility, making it imperative to evaluate these activities prior to application of CS as a nutraceutical ingredient. This work aims to appraise the effects of in vitro simulated gastrointestinal digestion on the bioaccessibility, bioactivity, and metabolic profiling of CS. An increase in the total phenolic and flavonoid contents, antioxidant/antiradical properties, radical scavenging capacity, and inhibition on acetylcholinesterase activity was evidenced during in vitro simulated digestion. Metabolomic profiling by LC-ESI-LTQ-Orbitrap-MS revealed changes during the simulated digestion, particularly in phenolic compounds (46% of total compounds annotated), lipids (22%), phenylpropanoids (9%), organic acids (7%), carbohydrates (5%), nucleosides (5%), amino acids (4%), and alcohols (1%). Phenolic acids (gallic acid, syringic acid, and hydroxyphenylacetic acid) and flavonoids (epicatechin) were the major polyphenolic classes identified. The heatmap-positive correlations highlighted that the bioactivity of CS is closely related to the phenolic compounds and their bioaccessibility. These findings suggest the reuse of CS as a potential nutraceutical ingredient with antioxidant and neuroprotective effects, encouraging the use of appropriate extraction and/or encapsulation techniques to enhance the bioaccessibility of phenolic compounds.
      Citation: Separations
      PubDate: 2023-08-28
      DOI: 10.3390/separations10090471
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 472: A Sensitive, Green, and Fast LC–MS/MS
           Analytical Method for the Quantification of Ribociclib: Evaluation of the
           Metabolic Stability in HLMs

    • Authors: Mohamed Attwa, Ali Abdelhameed, Adnan Kadi
      First page: 472
      Abstract: Ribociclib (Kisqali®) is a pharmacological agent that has great selectivity as a cyclin-dependent kinase 4/6 inhibitor. It has received regulatory approval for its application in the treatment of breast cancer. The objective of the current study was to develop a rapid, green, highly sensitive, validated, and specific LC–MS/MS approach for the quantification of RCB in human liver microsomes (HLMs) over the linear range of 1–3000 ng/mL (LLOQ: 0.98 ng/mL). The inter- and intraday precision and accuracy exhibited values ranging from −0.31% to 3.16% and −5.67% to 5.46% correspondingly. The eco-scale technique (AGREE program) was employed to examine the environmental impact of the existing LC–MS/MS technology. The in vitro half-life and intrinsic clearance of RCB were determined to be 23.58 min and 34.39 mL/min/kg, respectively, which indicated the intermediate extraction ratio of RCB. The in silico P450 software (version 6.6) was used to confirm and validate the practical results. The metabolism of RBC was previously studied by our research group, indicating that the piperazine ring and N-dimethyl group are responsible for the metabolic instability of RCB. Drug discovery studies can be conducted taking into account this concept, allowing the development of new drugs with an enhanced safety profile and good metabolic stability.
      Citation: Separations
      PubDate: 2023-08-28
      DOI: 10.3390/separations10090472
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 473: Composites Based on CaCl2-CaBr2 Salt
           System for Adsorption Applications: Designing the Optimal Sorbent for Gas
           Drying and Air Conditioning

    • Authors: Alexandra Grekova, Marina Solovyeva, Anastasiia Cherpakova, Mikhail Tokarev
      First page: 473
      Abstract: The different adsorption applications require the development of sorbents with predetermined properties. One of the ways for fine tuning the adsorption properties of the material is using a binary salt system as an active sorbing component. The aim of this work is to conduct a precision investigation of thermodynamic data on the sorption equilibrium of composite sorbents “(CaCl2 + CaBr2) confined to the silica gel pores” with water vapour. The isotherms and isosteres (at an uptake of N = 1.5 and 3.6 mole/mole) of water sorption on the composites were measured. It was shown that at a fixed temperature, the composites based on solid solutions of CaCl2 in CaBr2 form complexes with water at a pressure that is dependent on the CaCl2/CaBr2 molar ratio. The isosteric enthalpy and entropy of water sorption (ΔH = −48 ± 3 kJ/mol ΔS = −108 ± 2 J/(mol·K)) at N = 3.6 mole/mole were midway between the same parameters for composites on the base of the pure salts CaCl2 and CaBr2. The novelty of this work is in the design of sorbents optimized for air conditioning in hot climates and air drying cycles. It was shown that the use of the binary CaCl2 + CaBr2 system confined to the silica pores can be an effective tool for designing innovative materials with predetermined properties.
      Citation: Separations
      PubDate: 2023-08-28
      DOI: 10.3390/separations10090473
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 474: Application of a Quality by Design
           Approach to Develop a Simple, Fast, and Sensitive UPLC-MS/MS Method for
           Quantification of Safinamide, an Antiparkinson’s Drug, in Plasma

    • Authors: Essam A. Ali, Mohamed A. Ibrahim, Muzaffar Iqbal, Rashad Alsalahi, Gamal A. Mostafa, Suliman Al Jarboua
      First page: 474
      Abstract: Safinamide is an orally active, selective monoamine oxidase-B inhibitor with dopaminergic and non-dopaminergic properties approved by the European Medicine Agency and US Food and Drug Administration for the treatment of mid- to late-stage fluctuating Parkinson’s disease (PD) used in combination with other PD medications such as levodopa. In this study, an analytical quality by design (AQbD) approach was applied to optimize an LC-MS/MS bioanalytical method to determine safinamide in human plasma. A full 33 factorial design was used to optimize safinamide separation conditions, with a method first screened and optimized using chromatographic responses, including peak area and retention time. The results showed that temperature had a significant indirect effect on retention time and peak area (p < 0.05), while ammonium acetate concentration had an insignificant indirect impact on peak area or retention time. However, the temperature was significantly agonistic to the effect of buffer concentration (p < 0.05). The resultant optimized chromatography conditions utilized 9.0 mM ammonium acetate buffer and acetonitrile (22.0:78.0) as mobile phases at a column temperature of 23.2 °C. The assay was linear from 0.1–1000 ng/mL, met acceptance criteria for inter- and intra-assay precision and accuracies across three quality controls, and was successfully applied to in vitro microsomal metabolic stability. The UPLC/MS/MS method was found to be adequately sensitive and suitable for routine safinamide pharmacokinetic studies.
      Citation: Separations
      PubDate: 2023-08-28
      DOI: 10.3390/separations10090474
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 475: Fabrication and Characterization of
           Sulfonated Carbon Materials and Chitosan-Derived Functioned Carbon via
           Schiff’s Base Process for Separation Purposes

    • Authors: Ali S. Alghamdi, Kareem Yusuf, Mohamed A. Habila, Zeid A. ALOthman
      First page: 475
      Abstract: The Schiff bases reaction is applied to form various functioned carbon structures using renewable carbon from waste sources, Chitosan, 4-Amino-3-hydroxy-napthalene-1-sulphnic acid, and dimethyl amino benzaldehyde as starting materials. The formed functioned carbons were characterized by TEM, FTIR, XRD, and surface area analysis to assess their morphology, structure, porosity, and surface functional groups. In addition, the chromatographic-based thermodynamic analysis is applied to evaluate the surface energy and thermodynamic parameters during the separation of hydrocarbon species. Results indicated the formation of various carbon structures in convex-like shapes with diameters between 600 nm and 1500 nm, including side-building edges of diameter between 100 nm and 316 nm. The formed functioned carbon surfaces are rich with O-H, N=C, C=C, C=O, and C=S groups, as indicated by the FTIR. The function carbons are named carbon coated with Chitosan-derived covalent organic layer (C@Chitosan-COL) as well as Schiff’s base-derived sulfonated carbon (Schiff’s-C-S) in relation to the applied starting materials. The chromatographic-based thermodynamic analysis showed that the entropy changes of adsorption (ΔSA) increased with increasing chain length demonstrating less random movement and higher adsorption in both materials. The fabricated C@Chitosan-COL and Schiff’s-C-S showed an efficient separation of hydrocarbon mixture including n-Nonane, n-Decane, n-Undecane, and n-Dodecane.
      Citation: Separations
      PubDate: 2023-08-30
      DOI: 10.3390/separations10090475
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 476: Recent Advances in the Analysis of

    • Authors: Sascha Nowak
      First page: 476
      Abstract: Generally, “energies” can be defined as all the developments and applications regarding energy supply, conversion, application, and storage [...]
      Citation: Separations
      PubDate: 2023-08-31
      DOI: 10.3390/separations10090476
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 477: High Value Conversion Technology of
           Nickel in Waste Electrolytes of Nitrogen Trifluoride by Electrolysis

    • Authors: Yongzhuan Ren, Yuxuan Ran, Jiaqi Yang, Yonggang Wei
      First page: 477
      Abstract: The method of precipitation treatment of high-nickel waste electrolytic slag was studied, coupled with multi-step treatment to improve the recovery rate of nickel. In this study, HNO3 was used as dissolving agent, NaOH and Na2CO3 as precipitating agents, and the waste electrolytic slag was dissolved in the liquid phase and then precipitated. The results show that the electroslag with high nickel content can be completely dissolved under the optimal solid-liquid ratio of 1:10. When the pH of the leaching solution was adjusted to 7.5 by 5% NaOH solution, the iron removal rate could reach 99.3%. When the pH was adjusted to 11 with 5% Na2CO3, the nickel could be completely precipitated after standing, and the main component was basic nickel carbonate. The further recovery experiments show that high purity NiO can be obtained after the basic nickel carbonate is oxidized and calcined, and the average recovery rate of nickel is 92.4%. This study is of great practical significance to improve the treatment efficiency of the chemical precipitation method, reduce the operating cost of the chemical precipitation method, and reduce the production of secondary pollutants in the process of nickel recycling.
      Citation: Separations
      PubDate: 2023-08-31
      DOI: 10.3390/separations10090477
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 478: Isolation and Characterization of
           Triterpenoid Saponins from Ficus natalensis subsp. leprieurii Leaves

    • Authors: Samyah Alanazi, Shaimaa E. A. Elish, Abeer Temraz, Walid H. El-Tantawy, Mostafa H. Baky
      First page: 478
      Abstract: Ficus natalensis subsp. leprieurii also known as the natal fig is a fruit-producing tree belonging to the family Moraceae and widely distributed in African countries and cultivated in Egypt. F. natalensis is common with a myriad of traditional and medicinal importance. Owing to the increased demand for natural products with new structural compositions, the current study aimed to separate and elucidate the structure of triterpenoid saponins from F. natalensis leaves. Our previous biological investigation of F. natalensis leaves revealed its potent antioxidant and anti-inflammatory characteristics, and its ability to alleviate Cd-induced reproductive toxicity. Phytochemical investigation of F. natalensis leaves revealed the separation and structure elucidation of seven (1–7) compounds belonging to triterpenoid saponins using NMR and MS data and identified for the first time in F. natalensis. The isolated compounds were identified as 3-O-β-D-glucopyranosyl (1 → 4) β-D-glucopyranosyl (1 → 4)–α-L-rhamnopyranosyl-quinovic acid-28-O-β-D-glucopyranosyl (1 → 4)–α-L-rhamnopyranosyl (1 → 2)–α-L-arabinopyranoside ester (1), 3-O-β-D-glucopyranosyl (1 → 4) α-L rhamnopyranosyl-quinovic acid-28-O-β-D-glucopyranosyl (1 → 4)–α-L-rhamnopyranosyl (1 → 2) α-L-arabinopyranoside (2), 3-O-β-D-glucopyranosyl–quinovic acid-28-O-β-D-glucopyranosyl ester (3), as 3-O-α-L-rhamnopyranosyl-quinovic acid-28-O-β-D-glucopyranoside ester (4), 3-O-β-D-glucopyranosyl oleanolic acid (5), 3-methoxy-oleanolic acid-28-O-α-L-rhamnopyranoside (6), and 3-O-α-L-rhamnopyranosyl-oleanolic acid-28-O-β-D-glucopyranoside ester (7). Among the identified compounds, compounds 1 and 2 were identified for the first time in nature according to Reaxys and Web of Science database.
      Citation: Separations
      PubDate: 2023-08-31
      DOI: 10.3390/separations10090478
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 479: Chitosan and Metal Oxide Functionalized
           Chitosan as Efficient Sensors for Lead (II) Detection in Wastewater

    • Authors: Walid Boultif, Charif Dehchar, Youghourta Belhocine, Emna Zouaoui, Seyfeddine Rahali, Salah Eddine Zouari, Najoua Sbei, Mahamadou Seydou
      First page: 479
      Abstract: The work presented in this paper describes the preparation and the electrochemical application of functionalized chitosan-entrapped carbon paste electrodes (CH/CPE) for lead ions (Pb2+) detection in industrial wastewater. The chitosan was first functionalized using TiO2 and CuO, which were both metal oxides that were obtained by extracting it from waste products derived from shrimp shells. The analytical performance of the as-prepared electrodes, CH/CPE, TiO2-CH/CPE, and NiO-CH/CPE, for the detection of lead (II) was examined using electrochemical impedance spectroscopy (EIS) technique in the 0.1 M KNO3 electrolyte solution. The effect of experimental conditions, including polarization potential, frequency, and pH, are optimized to maximize the sensitivity of the measurements. The developed impedimetric sensors provided a linear response over a concentration range of 10−6 to 10−4 M with a detection limit of 3.10−7 M based on S/N = 3. The DFT computational analysis demonstrated that chitosan biopolymer possesses the ability to adsorb Pb (II) ions that are present in wastewater. Chitosan and the derivatives of chitosan, have the potential to remove heavy metals from industrial effluent in a manner that is both economical and eco-friendly to the environment. Chitosan is a biopolymer that is abundantly renewable.
      Citation: Separations
      PubDate: 2023-08-31
      DOI: 10.3390/separations10090479
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 480: Numerical Calculation and 3-D Imaging of
           the Arrhenius Temperature Integral

    • Authors: Wei Zhang, Qiaoyu Zheng, Xiaobing Yu, Yansong Shen, Kui Li
      First page: 480
      Abstract: The Arrhenius temperature integral is typically used in non-isothermal kinetic analysis, which is widely applied in gas–solid reactions in separation processes. In previous studies, researchers provided various methods to solve the temperature integral, but the error usually became significant when the value of x (x = Ea/RT) was too large or too small. In this paper, we present a new series method and design a computer program to calculate the temperature integral. According to the precise calculation of the temperature integral, we first reveal the relationship among the integral, the temperature, and the activation energy, and we find an interesting phenomenon in which the 3-D image of the temperature integral is of self-similarity according to fractal theory. The work is useful for mechanism and theoretical studies of non-isothermal kinetics.
      Citation: Separations
      PubDate: 2023-08-31
      DOI: 10.3390/separations10090480
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 481: Carnosic Acid and Carnosol: Analytical
           Methods for Their Determination in Plants, Foods and Biological Samples

    • Authors: Christiana Mantzourani, Petros A. Tarantilis, Maroula G. Kokotou
      First page: 481
      Abstract: Among the various phytochemicals, which are present in Lamiaceae plants, carnosic acid and carnosol stand out. Carnosic acid is a phenolic diterpene carrying two phenolic hydroxyl groups and a carboxyl group, while carnosol carries a lactone moiety in addition to phenolic hydroxyls. Both these phenolic diterpenes exhibit interesting biological properties, such as antioxidant, anticancer, anti-inflammatory and neuroprotective activities. In this review, we summarize the existing analytical methods for the determination of carnosic acid and carnosol, primarily in plants, but also in foods and biological samples. Due to the biological importance of carnosic acid and carnosol, a variety of analytical methods, including high-performance liquid chromatography–ultra violet (HPLC–UV), liquid chromatography–mass spectrometry (LC–MS) and capillary electrophoresis (CE), were developed for their determination. In addition, we discuss the extraction methods applied for their isolation from plants and in brief the bioactivities of these phytochemicals.
      Citation: Separations
      PubDate: 2023-09-02
      DOI: 10.3390/separations10090481
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 482: A Topic Modeling Approach to Discover the
           Global and Local Subjects in Membrane Distillation Separation Process

    • Authors: Ersin Aytaç, Mohamed Khayet
      First page: 482
      Abstract: Membrane distillation (MD) is proposed as an environmentally friendly technology of emerging interest able to aid in the resolution of the worldwide water issue and brine processing by producing distilled water and treating high-saline solutions up to their saturation with a view toward reaching zero liquid discharge (ZLD) at relatively low temperature requirements and a low operating hydrostatic pressure. Topic modeling (TM), which is a Machine Learning (ML) method combined with Natural Language Processing (NLP), is a customizable approach that is ideal for researching massive datasets with unknown themes. In this study, we used BERTopic, a new cutting-edge Python library for topic modeling, to explore the global and local themes in the MD separation literature. By using the BERTopic model, the words describing the collected dataset were detected together with over- and underexplored research topics to guide MD researchers in planning their future works. The results indicated that two global themes are widely discussed and are relevant to MD scientists abroad. In brief, these topics are permeate flux, heat-energy recovery, surface modification, and polyvinylidene fluoride hydrophobic membranes. BERTopic discovered 62 local concepts. The most researched local topics were solar applications, membrane scaling, and electrospun membranes, while the least investigated were boron removal, dairy effluent applications, and nickel wastewater treatment. In addition, the topics were illustrated in a 2D plane to better understand the obtained results.
      Citation: Separations
      PubDate: 2023-09-02
      DOI: 10.3390/separations10090482
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 483: Sequential Separation of Essential Oil
           Components during Hydrodistillation of Azorean Cryptomeria japonica
           Foliage: Effects on Yield, Physical Properties, and Chemical Composition

    • Authors: Filipe Arruda, Ana Lima, Tanner Wortham, Alexandre Janeiro, Tânia Rodrigues, José Baptista, José S. Rosa, Elisabete Lima
      First page: 483
      Abstract: The hydrodistillation (HD) process is used to obtain and fractionate essential oils (EOs). In this study, we aimed to evaluate, for the first time, the effects of six different HD timeframes (HDTs: 0–2, 2–10, 10–30, 30–60, 60–120, and 120–240 min) on the yield, physical properties, and chemical profile of Azorean Cryptomeria japonica foliage (Az–CJF) EO. An Az–CJF EO obtained by a typical HD over 4 h was used as a control sample, yielding 0.82%, w/fresh weight (f.w.), and containing eighty-nine components, as determined by GC–MS. The EO fraction yield revealed a narrow range (0.06–0.18%, w/f.w.), with ca. 50% obtained within the first hour. Monoterpene hydrocarbons dominated in Fr1 and Fr2 (92 and 45%, respectively, mainly α-pinene) while oxygen-containing sesquiterpenes prevailed in Frs. 3–6 (42–62%, mainly elemol and eudesmol isomers). Furthermore, Fr2 and Fr3 were the richest in oxygen-containing monoterpenes (9 and 7%, respectively, mainly bornyl acetate) and in sesquiterpene hydrocarbons (6 and 5%, respectively, mainly δ-cadinene), while Fr4 and Fr5 had higher amounts of diterpene hydrocarbons (ca. 22% both, mainly phyllocladene) and Fr6 exhibited the highest oxygen-containing diterpenes content (4%, mainly nezukol). In addition, regression models were established to predict EO yield, HD rate, and composition (major components) for a given HDT. As a result of this study, specific EO fractions can now be targeted in Az–CJF EO by adjusting the HDT. Hence, these findings can help reduce distillation time and, thus, operating costs associated with the HD process. It can also meet specific market demands due to the differential composition of the obtained EO fractions. In turn, this contributes to increasing the commercial potential of C. japonica EO.
      Citation: Separations
      PubDate: 2023-09-02
      DOI: 10.3390/separations10090483
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 484: GC-MS Analysis of Essential Oil and
           Volatiles from Aerial Parts of Peucedanum tauricum M.B. during the
           Phenological Period

    • Authors: Magdalena Bartnik
      First page: 484
      Abstract: Widespread worldwide Peucedanum plants (Apiaceae) have been used for centuries as plant medicines. The polymorphism of this genus is consistent with chemotaxonomically and therapeutically significant differences in the composition of secondary metabolites. GC-MS of Peucedanum tauricum M.B. volatiles from the headspace (HS) and hydrodistilled essential oil (HD), both obtained simultaneously from flowers (FL), immature and ripe fruits (IF, MF) and leaves (L1-L3) collected at the time of harvesting of generative organs, show differences in the chemical profiles of HS and HD from the same parts of the plant, and between organs (FL, IF, MF vs. L1-L3). The presented studies on the variability of biometabolites in the phenological period indicated the optimal harvesting time, focused on two molecular chemotaxonomic markers of PT; guaia-1(10),11-diene and guaia-9,11-diene (in generative organs iHD at 25.5–32.1% and 26.8–33.6%; and in their HS at 29.4–41.3% and 25.0–29.4%, respectively). This is the first report on the analysis of fresh aerial parts of Peucedanum sp. in which GC-MS of HS and HD was performed simultaneously during the vegetation period. The importance, with possible limitations, of GC-MS analysis of HS and HD as an evaluation tool useful in the chemotaxonomy of Peucedanum plants was also discussed.
      Citation: Separations
      PubDate: 2023-09-04
      DOI: 10.3390/separations10090484
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 485: Optimizing Membrane Distillation
           Performance through Flow Channel Modification with Baffles: Experimental
           and Computational Study

    • Authors: Yaoling Zhang, Xingsen Mu, Jiaqi Sun, Fei Guo
      First page: 485
      Abstract: It has been identified that temperature polarization and concentration polarization are typical near-surface phenomena limiting the performance of membrane distillation. The module design should allow for effective flow, reducing the polarization effects near the membrane surfaces and avoiding high hydrostatic pressure drops across and along the membrane surfaces. A potential route to enhancing the membrane distillation performance is geometry modification on the flow channel by employing baffles as vortex generators, reducing the polarization effects. In this work, various baffles with different structures were fabricated by 3D printing and attached to the feed flow channel shell in an air gap membrane distillation module. The hydrodynamic characteristics of the modified flow channels were systematically investigated via computational fluid dynamics simulations with various conditions. The membrane distillation tests show that adding the baffles to the feed channel can effectively increase the transmembrane flux. The transmembrane flux with rectangular baffles and shield-shaped baffles increases by 21.8% and 28.1% at the feed temperature of 70 °C. Moreover, the shield-shaped baffles in the flow channel not only enhance the transmembrane flux but also maintain a low-pressure drop, making it even more significant.
      Citation: Separations
      PubDate: 2023-09-05
      DOI: 10.3390/separations10090485
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 486: Mycotoxins and Maize Value Chain:
           Multi-Matrix and Multi-Analyte Tools towards Global Feed and Food Safety

    • Authors: Marta Leite, Andreia Freitas, Jorge Barbosa, Fernando Ramos
      First page: 486
      Abstract: Maize value chains represent invaluable end-consumer products in food systems worldwide. Mycotoxin contamination along these chains causes severe economic and health impacts from the plant, animal and human safety points of view. This work aimed to develop a single standardized methodology that fulfilled extraction and detection procedures for 22 mycotoxins in maize chain matrices. The main goal concerned the validation of a QuEChERS-based ultra-high-performance liquid chromatography coupled to the tandem mass spectrometry (UHPLC-MS/MS) method in compliance with established performance criteria for mycotoxin determination. Validation parameters encompassing specificity/selectivity, linearity, precision, recovery, Limits of Detection (LOD) and Limits of Quantification (LOQ) were evaluated, and acceptable data were found for all the mycotoxins in the matrices under study, namely, seeds, flowering plants, silage and feed. The applied method presented LODs and LOQs lower than 40.3 and 42.1 ng g−1, respectively, and recoveries ranging from 80.7 to 118.1%, with precision values below 20.5%. A first-time full analytical procedure in a multi-matrix and multi-analyte approach was successfully validated, representing a valuable control tool for mycotoxin monitoring in maize chains. This approach will ultimately allow a response to the need for integrated risk assessments encompassing full, comprehensive analysis of whole food chains in compliance with the maximum levels established in European regulations, and the establishment of accurate solutions in each chain-specific critical point, helping to provide more sustainable, safer and healthy food systems.
      Citation: Separations
      PubDate: 2023-09-05
      DOI: 10.3390/separations10090486
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 487: Shaping of HKUST-1 via Extrusion for the
           Separation of CO2/CH4 in Biogas

    • Authors: Muhamad Tahriri Rozaini, Denys I. Grekov, Mohamad Azmi Bustam, Pascaline Pré
      First page: 487
      Abstract: HKUST-1 is a metal-organic framework (MOF) that is widely studied as an adsorbent for CO2 capture because of its high adsorption capacity and good CO2/CH4 selectivity. However, the numerous synthesis routes for HKUST-1 often result in the obtention of MOF in powder form, which limits its application in industry. Here, we report the shaping of HKUST-1 powder via the extrusion method with the usage of bio-sourced polylactic acid (PLA) as a binder. The characterization of the composite was determined by XRD, FTIR, TGA and SEM analyses. The specific surface area was determined from the N2 adsorption isotherm, whereas the gas adsorption capacities were investigated via measurements of CO2 and CH4 isotherms of up to 10 bar at ambient temperature. The material characterization reveals that the composite preserves HKUST-1’s crystalline structure, morphology and textural properties. Furthermore, CO2 and CH4 adsorption isotherms show that there is no degradation of gravimetric gas adsorption capacity after shaping and the composite yields a similar isosteric adsorption heat as pristine HKUST-1 powder. However, some trade-offs could be observed, as the composite exhibits a lower bulk density than pristine HKUST-1 powder and PLA has no impact on pristine HKUST-1’s moisture stability. Overall, this study demonstrates the possibility of shaping commercial HKUST-1 powder, using PLA as a binder, into a larger solid-state-form adsorbent that is suitable for the separation of CO2 from CH4 with a well-preserved pristine MOF gas-adsorption performance.
      Citation: Separations
      PubDate: 2023-09-06
      DOI: 10.3390/separations10090487
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 488: An In-Depth Stability Study of the
           Essential Oils from Mentha × piperita, Mentha spicata, Origanum
           vulgare, and Thymus vulgaris: The Impact of Thermal and Storage Conditions

    • Authors: Eugenia Ganosi, Christina Barda, Maria-Eleni Grafakou, Michael Ch. Rallis, Helen Skaltsa
      First page: 488
      Abstract: In recent years, there has been a growing scientific interest in essential oils due to their therapeutic and aromatic properties and as potential alternative natural additives for use as preservatives or antibiotics. However, the literature lacks a comprehensive understanding of their stability and how their composition and properties change over time under various conditions. Through this paper, we aim to enhance the existing literature by providing deeper insights into the stability of essential oils and the sustainability of chemical composition in a time-based approach under various conditions. Therefore, four essential oils of the Lamiaceae family (Origanum vulgare, Thymus vulgaris, Mentha spicata, and M. x piperita) were evaluated with respect to their chemical variation influenced by several factors, such as thermal and storage conditions. Three types of containers were utilized to store the essential oils, i.e., glass ampoules, glass tubes, and metallic containers with plastic caps, for up to six months in −20 °C, 4 °C, 23 °C (with or without light exposure), 35 °C, and 45 °C. Samples were routinely analyzed by GC-MS and components were subjected to principal component analysis to ascertain whether the identified constituents may be useful in reflecting the stability of the analyzed samples. The main compounds appeared to be more stable, while the degradation of minor constituents (<1.0%) occurred in all four essential oils despite the storage conditions. Overall, apart from a slight variation in the chemical load, essential oils can be considered stable for various applications, especially those stored under low oxygen availability conditions.
      Citation: Separations
      PubDate: 2023-09-07
      DOI: 10.3390/separations10090488
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 489: Advances in Hydrocarbon Speciation for
           Soil Gas Analysis

    • Authors: Maria Antonietta De Gregorio, Laura Clerici, Emma Marinone, Valeria Frattini, Pierluisa Dellavedova
      First page: 489
      Abstract: In the field of contaminated site remediation, risk analyses can be carried out by the use of appropriate mathematical models, based on simplified hypotheses of real sites. The possibility to have shared and accurate analytical methods is an important challenge for both routine laboratories and supervisory institutions. Although official methods (e.g., APH2009) are already available, they are lacking in some aspects, such as applicability to all the different sampling and analysis media and ease of use in routine analysis. Here, we report our recent advances in the implementation of an empirical method for hydrocarbon speciation in an air matrix, previously developed by the authors and published in 2015. The validation results led to a coefficient of variation (CV%) between 10–15% for the hydrocarbon fractions investigated (C5-C8 aliphatic, C9-C12 aliphatic, C9-C10 aromatic and C11-C12 aromatic) and recovery of ≤20%, in agreement with the required characteristics for the analytical methods. Several real samples were analyzed by the proposed method and the results were compared to those obtained by the official approach. The comparison led to an average bias (that is, the difference between the results from the developed method and those from the conventional one) of about 10%, confirming that the innovative approach is robust, accurate and can be applied to all the analytical media used for air sampling, such as soil gas.
      Citation: Separations
      PubDate: 2023-09-07
      DOI: 10.3390/separations10090489
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 490: Analysis of Status Quo of Research on
           Heavy Metals in Rivers and Lakes Based on Bibliometrics

    • Authors: Shuhang Wang, Yaran Zhang, Zhenghui Fu, Dong Shi, Yuanyi Wang, Dianhai Yang, Feifei Che
      First page: 490
      Abstract: Heavy metal pollution in rivers and lakes arising due to rapid economic development has been extensively studied by various countries due to its direct impact on ecological health and human well-being. However, there is a lack of comprehensive and systematic reviews addressing the current research status of this subject. In this study, we conducted a visual metrological analysis of the literature from 2001 to 2021 using the Web of Science (WoS) and China National Knowledge Infrastructure (CNKI) citation databases. The results show that studies conducted in other countries initially outnumbered those in China; after 2010, China emerged as the foremost contributor. Furthermore, both the WoS and CNKI databases indicate active engagement of Chinese researchers through a significant proportion of published papers on metal research, with prominent contributions coming from institutions such as the Chinese Academy of Sciences (CAS) and University CAS. Nevertheless, Chinese research institutions still have relatively low total paper citation numbers and have yet to establish themselves as key players in international scientific research efforts. Additionally, core authors from different countries share substantial similarities in their research directions and focuses. Consistent research hotspots regarding heavy metals in rivers and lakes were identified across both databases, including heavy metal pollution, adsorption, human activities, water quality, and sediment.
      Citation: Separations
      PubDate: 2023-09-07
      DOI: 10.3390/separations10090490
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 491: Cross-Contamination of Ignitable Liquid
           Residues on Wildfire Debris—Detection and Characterization in
           Matrices Commonly Encountered at Wildfire Scenes

    • Authors: Nadin Boegelsack, James Walker, Court D. Sandau, Jonathan M. Withey, Dena W. McMartin, Gwen O'Sullivan
      First page: 491
      Abstract: Ignitable liquid residue (ILR) samples play an important role in fire investigations. Similar to other types of forensic evidence, maintaining sample integrity depends on the prevention of cross-contamination during both storage and transport. This study examines cross-contamination in ILR samples on various sample matrices (gravel, soil, wood). After inducing leaks in a controlled environment, sample analysis by GC×GC-ToF MS allowed for sensitive detection and in-depth characterization of cross-contamination processes. The potential for false positive identification of ILR is notably present due to cross-contamination. Compound transmission for a mid-range ILR (gasoline), for instance, was detectable after a 1 h exposure, with a complete profile transfer occurring after 8 h regardless of the matrix type. Visual comparisons and uptake rate calculations further confirmed matrix interaction effects taking place in the form of inherent native compound interference and adsorbate–adsorbate interaction during transmission and extraction processes for soil and wood matrices. Chemometric analysis highlighted the advantage of employing statistical analysis when investigating samples under matrix interactions by identifying several statistically significant compounds for reliably differentiating cross-contamination from background and simulated positive samples in different volatility ranges and compound classes. Untargeted analysis tentatively identified three additional compounds of interest within compound classes not currently investigated in routine analysis. The resulting classification between background, contaminated, and simulated positive samples showed no potential for false positive ILR identification and improved false negative errors, as evidenced by classification confidences progressing from 88% for targeted and 93% for untargeted to 95% for a diagnostic ratio analysis of three ratios deployed in tandem.
      Citation: Separations
      PubDate: 2023-09-11
      DOI: 10.3390/separations10090491
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 492: The Competitive Adsorption of Water and
           Methanol on a Hybrid Silica Stationary Phase in Supercritical Fluid

    • Authors: Muhamad Yahia Kazmouz, Attila Felinger
      First page: 492
      Abstract: This study investigates the adsorption of methanol, water, and their mixture in a hybrid silica stationary phase with supercritical carbon dioxide as a mobile phase in supercritical fluid chromatography (SFC). The adsorption isotherms of methanol and water were determined by two dynamic methods: the elution by characteristic point (ECP) method and the inverse method (IM). Both the single-component and competitive bi-Langmuir models were pre-selected for the inverse method. The initial parameters of the single-component isotherm for both methanol and water were estimated with the ECP method by fitting the experimental data to the bi-Langmuir isotherm model. Then, using the inverse method, we refined the single-component isotherm parameter values, which were then further used for determining the competitive isotherm of the methanol–water mixture. The elution profile of the (methanol–water) mixture sample was calculated by the equilibrium-dispersive (ED) model. The results indicated that there is a good agreement between the experimental band profile and the calculated band profile, which was obtained from the parameters of the competitive bi-Langmuir isotherm model, revealing a competition between methanol and water to reach the adsorption sites. Furthermore, the saturation capacity of the adsorption sites in the stationary phase decreased in the case of the mixture sample compared to those for the single-component sample.
      Citation: Separations
      PubDate: 2023-09-11
      DOI: 10.3390/separations10090492
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 493: Adsorptive Removal of Emulsified
           Automobile Fuel from Aqueous Solution

    • Authors: Mohammad Asif, Mourad M. Boumaza, Nadavala Siva Kumar, Ebrahim H. Al-Ghurabi, Mohammed Shahabuddin
      First page: 493
      Abstract: The development of cost-effective technologies for the treatment of water contaminated by petrochemicals is an environmental priority. This issue is of paramount importance for countries like Saudi Arabia owing to its scarce water resources. Of particular concern are automobile fuels, such as gasoline and diesel, that can contaminate water aquifers from leaking underground fuel storage tanks. Owing to the cost-effectiveness of adsorption-based technologies, low-cost high surface-area commercial activated carbon was used for the adsorptive removal of contaminants from the emulsified fuel-contaminated water. Batch equilibrium experiments showed a high efficacy of the adsorbent. Even with small amounts of the adsorbent, a removal efficiency of more than 97% was obtained for both gasoline as well as diesel. Three different well-known batch adsorption isotherm models, namely the Langmuir, Freundlich, and Temkin, were used for describing the experimental data. The best results were obtained using the Freundlich isotherm followed by the Langmuir model. The maximum capacity was found to be 8.3 g gasoline and 9.3 g diesel per gram of the adsorbent at ambient conditions for a neutral contaminated aqueous solution.
      Citation: Separations
      PubDate: 2023-09-11
      DOI: 10.3390/separations10090493
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 494: Development and Validation of an
           Ecofriendly, Rapid, Simple and Sensitive UPLC-MS/MS Method for Entrectinib
           Quantification in Plasma for Therapeutic Drug Monitoring

    • Authors: Essam A. Ali, Muzaffar Iqbal, Gamal A. E. Mostafa, Rashad Al Salahi
      First page: 494
      Abstract: Entrectinib is an oral selective inhibitor of the neurotrophic T receptor kinase (NTRK). It is used in the treatment of solid tumors in NTRK gene fusion lung cancer. The study aimed to develop and validate an analytical method for quantifying entrectinib plasma by UPLC-MS/MS using quizartinib as an internal standard. The method involves liquid–liquid extraction of entrectinib from plasma using tert butyl methyl ether. The mass-to-charge transitions were 561.23 → 435.1 for entrectinib and 561.19 → 114.1 for quizartinib. The method was successfully validated according to ICH and FDA guidelines. The method has a low quantification limit of 0.5 ng/mL, and the calibration curves constructed over a wide range of 0.5–1000 ng/mL showed good linearity (≥0.997). This method exhibits a tenfold increase in sensitivity compared with the previous method. The method is also accurate, precise, and reproducible, as evidenced by the inter-day and intra-day accuracy and precision values of 82.24–93.33% and 3.64–14.78%, respectively. Principles of green analytical chemistry were considered during all analytical steps to ensure safety. The greenness of the methods was evaluated using two assessment tools. These tools are the Analytical Eco-Scale and the analytical greenness metric approach (AGREE). The results were satisfactory and compatible with the criteria of these tools for green assessment. This method is green, accurate, precise, and reproducible. The method can be used to quantitate entrectinib in plasma and its pharmacokinetics in preclinical, and therapeutic drug monitoring.
      Citation: Separations
      PubDate: 2023-09-11
      DOI: 10.3390/separations10090494
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 495: Application of Response Surface Method
           for Determination of Optimized Conditions for Quantification of
           1,4-Dioxane in Model System of Polyethylene Glycol 200

    • Authors: Myung-Chan Kim, Su-Yeon Park, Hyo-Rim Kim, Yun-Sung Cho, Tabu Mungia Magollah, Jin Hong Mok, Yang-Bong Lee
      First page: 495
      Abstract: The release of 1,4-dioxane probably contributes to the deterioration of marine habitats, animal health, and human liver and kidneys. The formulation of 1,4-dioxane in glycols, which has been applied for dehumidifying agents in refineries, may need to be replaced to ensurepublic health. Further, it is necessary to identify and precisely determine the levels of 1,4-dioxane in glycols for food quality control and environmental safety regulation. The objectives of this study were to validate a liquid–liquid extraction (LLE) method for 1,4-dioxane analysis and to optimize the LLE conditions using a response surface methodology (RSM). With consideration of the food matrix and its applications, polyethylene glycol 200 was used as the model system and analyzed by gas chromatography with flame ionization detection. In the experiments for the optimum extraction temperature and time of 1,4-dioxane in ultrasonic treatment, they were 20 °C and 10 min, respectively. The experimental conditions and results were analyzed by RSM with the Box–Behnken design, and the optimal extraction conditions for the LLE were determined to be coded with three independent variables (sample weight, solvent volume, and centrifugation speed). The amount of 1,4-dioxane increased as the amount of sample increased, whereas the amount of 1,4-dioxane decreased as the amount of solvent increased. This information can help to find the analytical methods for regulating the 1,4-dioxane content and its precise quantification in food products.
      Citation: Separations
      PubDate: 2023-09-12
      DOI: 10.3390/separations10090495
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 496: Separation and Isolation of a New
           Hydroxylated Resveratrol Trimer Together with Other Stilbenoid Compounds
           from the Lianas of Gnetum microcarpum Blume and Their Inhibitory Effects
           of Prostaglandin E2

    • Authors: Nik Fatini Nik Azmin, Norizan Ahmat, Juriyati Jalil, Carla Wulandari Sabandar, Nik Khairunissa’ Nik Abdullah Zawawi, Siti Norafiqah Mohd Sazali, Mohd Izwan Mohamad Yusof, Aisyah Salihah Kamarozaman, Mulyadi Tanjung
      First page: 496
      Abstract: A new oligostilbene trimer, malaysianol F (1), together with ten known stilbenes (2–11), were successfully separated and purified from the acetone extract of the lianas of Gnetum microcarpum. Malaysianol D (2) was isolated for the first time in Gnetum plants. The tanninless crude extract (52.5 g) was fractionated using a vacuum liquid chromatography (VLC) technique to give five major fractions. Fraction 2 (4.68 g), 3 (4.79 g) and 4 (9.29 g) were all subjected to further isolation and purification using VLC, column chromatography (CC) and repetitive radial chromatography (RC) techniques with the best solvent system to yield malaysianol F (1) (6.2 mg), malaysianol D (2) (62.5 mg), malaysianol E (3) (2.4 mg), ε-viniferin (4) (10 mg), resveratrol (5) (6.5 mg), gnetol (6) (3.5 mg), gnetucleistol C (7) (12.2 mg), isorhapontigenin (8) (8 mg), cuspidan B (9) (3.2 mg), parvifolol D (10) (4.8 mg) and gnetifolin M (11) (2.5 mg). Their structures were determined on the basis of the analysis of spectral evidence by extensive NMR data analyses and comparison with the related published data. Several compounds were tested for anti-inflammatory activity. Their inhibitory effect on Prostaglandin E2 (PGE2) was tested using radioimmunoassay techniques. Compound 6 exhibited significant concentration-dependent inhibitory effects on PGE2 production with IC50 values of 1.84 µM comparable with the positive control, indomethacin (IC50 1.29 µM).
      Citation: Separations
      PubDate: 2023-09-12
      DOI: 10.3390/separations10090496
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 497: A New Sample Processing Protocol for
           Separation and Purification Enabling Precise Analysis of Various
           Non-Traditional Isotopes in Geological Samples with Low Concentrations

    • Authors: Jianye Gui, Wei Zou
      First page: 497
      Abstract: Many non-traditional isotopes, such as chlorine, magnesium, calcium, etc., are widely used as groundwater tracers. A new sample processing protocol of purification and concentration for isotopic analysis is presented to overcome many of the major drawbacks of existing methods. Contemporary sample preparation often requires several laborious off-line procedures in a ultra clean laboratory prior to instrumental determination; additionally, interference ions in real samples are difficult to completely remove, especially when the concentration of those ions is equal to that of the target ions. The new protocol includes the following steps: (i) one-step purification using a newly developed isotopic preparative chromatograph (IPC) with a background suppressed mode to obtain extremely pure components that only have target ions and H2O; (ii) enrichment of the collected pure solution from the previous step using a newly developed ultra clean concentrator filled with high purity nitrogen; (iii) transforming the enriched target ion into suitable speciation inside the ultra clean concentrator; (iv) finally, sending the enriched solutions to a multi-collector inductively coupled-plasma mass-spectrometer (MC-ICP-MS) or thermal ionization mass spectrometer (TIMS). The present method was validated using certified reference materials and real samples for both chlorine and magnesium; the precision of chlorine ratio value was generally below 0.22‰ and that of Mg was below 0.12‰. This processing protocol provides a potential method for isotope sample preparation and analysis in a small number of geological samples with low concentrations of many other elements or compounds such as nitrate, sulfate, lithium, calcium, strontium, etc.
      Citation: Separations
      PubDate: 2023-09-12
      DOI: 10.3390/separations10090497
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 498: Properties of Glass-Ceramics Prepared
           from Industrial Multi-Wastes

    • Authors: Zuoliang Zhang, Heli Ma, Chunlei Wu, Ye Sun, Ren Chen, Xiaoying Guo
      First page: 498
      Abstract: Because of their excellent properties, glass-ceramics have been widely developed and applied in many fields, and there are many potential application values to be disseminated. The preparation of glass-ceramics from industrial slag and metallurgical waste provides a new way for the comprehensive utilization of solid waste. Coal gangue is the largest of all kinds of industrial waste slag, while iron tailings and high-carbon ferrochrome slag also occupy a large proportion of China’s industrial solid waste. With cheap industrial solid waste as the main raw material, the production of high-value-added glass-ceramics can reduce pollution, protect the ecological environment, and have good economic and social benefits. Cordierite glass-ceramics were prepared using the sintering method with coal gangue, iron tailings, and high-carbon ferrochrome slag as the main raw materials. Meanwhile, an iron silicon alloy containing chromium was obtained. The heat treatment system of basic glass was determined by differential scanning calorimetry (DSC), and the sintered product was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). An orthogonal test was used to analyze the effects of the mass of basic glass powder, molding pressure, and holding time on the grain size and crystallinity of the samples. The hardness, acid and alkali resistance, density, and water absorption of the sintered products were determined. The results show that the main crystal phase of the prepared glass-ceramics is cordierite. The optimal combination for the green body is “basic glass powder mass 6 g, molding pressure 35 MPa, holding time 10 min”. The properties of glass-ceramics are good. At the crystallization temperature of 970 °C, the Vickers hardness is up to 866 HV, and the bulk density is up to 2.99 g/cm3. This study may provide a useful reference for the treatment of industrial solid waste.
      Citation: Separations
      PubDate: 2023-09-12
      DOI: 10.3390/separations10090498
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 499: Molecular Simulations of the Gas
           Diffusion through the Two-Dimensional Graphyne Membrane

    • Authors: Dongliang Jin, Tao Zhang, Meng Guo, Nanhua Wu, Jing Zhong
      First page: 499
      Abstract: Owing to the unified and tunable pore size, two-dimensional graphyne membranes show excellent performance in the realm of gas transport and separations. The impacts of environmental conditions on the pore size of a porous membrane are ignored in previous studies. Using molecular modeling techniques, we here probe the accessible pore size of the γ-graphyne membrane under various pressure and temperature conditions. First, by assessing the gas permeation through the two-dimensional γ-graphyne membrane at a constant temperature, the accessible pore size of this membrane is shown to be proportional to the driving force—the pressure difference between the two sides of the porous membrane. Such a driving force dependence is found to be well described by a simple asymptotic model. Then, by determining such pressure dependence at two different temperatures, temperature is found to show a weak influence on the accessible pore size. Finally, by considering the binary mixed gases of various mole fractions, the accessible pore size measured using one of the two species is shown to be dependent on its partial pressure difference. These findings for the accessible pore size, which highlight the tunable pore size by altering the driving force, can be expected to provide a practical strategy to rationalize/refine the pore size of the porous membrane for gas transport and separations, especially for two molecules with similar diameters.
      Citation: Separations
      PubDate: 2023-09-13
      DOI: 10.3390/separations10090499
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 500: Comprehensive Profiling of Terpenes and
           Terpenoids in Different Cannabis Strains Using GC × GC-TOFMS

    • Authors: Jasmeen Kaur, Ning Sun, Jane E. Hill
      First page: 500
      Abstract: Cannabis contains a wide range of terpenes and terpenoids that are mainly responsible for their distinctive aroma and flavor. These compounds have also demonstrated therapeutic effects either alone and/or as synergistic compounds with other terpenes, terpenoids, and/or cannabinoids. Several studies have attempted to fully characterize terpenes and terpenoids in cannabis; however, most of these studies used one-dimensional gas chromatography, which often results in the co-elution of the compounds. In the present study, we analyzed terpenes and terpenoids in the dried flowers of six cannabis strains using a two-dimensional gas chromatograph time-of-flight mass spectrometer (GC × GC-TOFMS). A total of 146 terpenes and terpenoids were detected across all six cannabis strains with an enhanced separation of 16 terpenes and terpenoids in the second dimension. Additionally, we achieved enhanced separation of four terpenes and terpenoids from a standard mixture in the second dimension. Chemical differences were observed in the number and relative abundance of monoterpenes, monoterpenoids, sesquiterpenes, and sesquiterpenoids in all six strains. We were also able to identify four new terpenoids in cannabis, which are reported here for the first time.
      Citation: Separations
      PubDate: 2023-09-13
      DOI: 10.3390/separations10090500
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 501: Insights into the Adsorption Performance
           of Emerging Contaminants on Granular Activated Carbon

    • Authors: Sang-Hoon Lee, Namgyu Kim, Donghee Park
      First page: 501
      Abstract: Emerging contaminants are being detected at a high frequency, posing significant environmental and human health challenges. This study aimed to investigate the potential of using commercial granular activated carbon for adsorbing nine aqueous emerging contaminants (carbamazepine, phenacetin, pentoxifylline, norfloxacin, iprobenfos, isoprothiolane, metolachlor, tebuconazole, and hexaconazole). The adsorption study involved employing kinetic and isotherm models, using various concentrations of emerging contaminants and sorbents in a batch system. Additionally, the study explored the correlation between the characteristics of emerging contaminants and their adsorption values, which displayed a relatively linear relationship. While some previous papers have evaluated the performance of one or two substances, there is a lack of research on the adsorption mechanisms of all nine aqueous emerging contaminants. Therefore, the findings from this study on the adsorption potential of granular activated carbon can serve as a valuable foundation for further investigations into its effectiveness in adsorbing emerging contaminants.
      Citation: Separations
      PubDate: 2023-09-13
      DOI: 10.3390/separations10090501
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 502: Determination of Lysergic Acid
           Diethylamide and 2-Oxo-3-Hydroxy-LSD in Blood: Validation and Comparison
           of Two Liquid Chromatography–Tandem Mass Spectrometry Methods

    • Authors: Alexandra Dimitrova, Maria Grazia Di Milia, Regina Rensi, Simone Grassi, Barbara Gualco, Fabio Vaiano
      First page: 502
      Abstract: Lysergic acid diethylamide (LSD) is a powerful hallucinogen. Its detection is limited by its low dosage; moreover, LSD is rapidly metabolized into 2-oxo-3-hydroxy-LSD (O-H-LSD). In this study we validated two methods for determination of LSD and O-H-LSD in blood. Method #1 consisted in the upgrade of a previously developed procedure for detection of 163 compounds. Method #2 was specific for LSD and O-H-LSD. Analyses were performed through LC-MS/MS by dynamic (#1) and/or MRM mode (#2), in positive ionization. Transitions were: 324→223,208 m/z for LSD; 356→237,222 m/z for O-H-LSD. Validations were performed following the AAFS’s guidelines. Linearity was good for both methods. Sensitivity was in line with previously validated methods with LOQs at 0.0375 (#1) and 0.025 (#2) ng/mL for LSD and 0.01875 (#1) and 0.0125 (#2) ng/mL for O-H-LSD. Bias and %CV always met the acceptance criteria. RRs were >83%, except for O-H-LSD with method #1. The methods were successfully applied to two real cases. Method #1 proved to be useful for screening purposes, while method #2 can represent a sensitive and reliable tool for confirmation procedures.
      Citation: Separations
      PubDate: 2023-09-14
      DOI: 10.3390/separations10090502
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 503: Determining Polycyclic Aromatic Compounds
           in Bird Feathers Using Pressurized Fluid Extraction

    • Authors: Vida Moradi, Thor Halldorson, Zhe Xia, Nipuni Vitharana, Chris Marvin, Philippe J. Thomas, Manon Sorais, Glenn T. Crossin, Gregg Tomy
      First page: 503
      Abstract: Due to their ease of collecting and transporting from the field and their ability to accumulate pollutants, bird feathers are increasingly being used as a non-invasive biomonitoring tool for environmental monitoring programs. Polycyclic aromatic compounds (PACs) are a diverse class of environmental pollutants, and because of their deleterious impacts on biological species, monitoring these compounds in wildlife is of high importance. Current approaches to measuring PACs in bird feathers involve a time-consuming acid treatment with a concomitant solvent extraction step. Here, a validated method for measuring a suite of PACs in bird feathers using pressurized fluid extraction and identification and quantitation by gas chromatography-tandem mass spectrometry is presented. Chicken (Gallus domesticus) feathers were purposely fortified with a suite of 34 PACs separately at three fortification levels and placed inside a pressurized fluid extraction cell containing silica gel/deactivated alumina to provide in situ clean-up of the sample. Except for anthracene and naphthalene, the accuracy of our method ranged for PAHs from 70–120% (irrespective of fortification level), and our intra- and inter-day repeatability was smaller than 28%. For APAHs, our accuracies ranged from 38–158%, and the inter- and intra-day repeatability was less than 35%. Our limits of detection and quantitation for both groups of compounds ranged from 0.5–13 and 1.5–44.3 ng/g, respectively. Overall, the developed method represents an effective and efficient approach for the extraction and quantitation of PACs from bird feathers that negated the need for the time-consuming and potentially harmful acid treatment.
      Citation: Separations
      PubDate: 2023-09-14
      DOI: 10.3390/separations10090503
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 504: Application of Magnetic Field to
           Accelerate the Crystallization of Scopolamine Hydrobromide

    • Authors: Zeyu Wu, Pengpeng Chen, Huixi Bian, An Zhou, Kun Xu, Wencheng Zhang
      First page: 504
      Abstract: In this paper, a rapid and efficient method for the preparation of scopolamine hydrobromide with high purity was established, named as magnetic field-induced crystallization. Based on the difference in solubility between scopolamine and scopolamine hydrobromide, salifying crystallization was selected and then treated with the synergistic effect of magnetic field to achieve the goal of purifying scopolamine. The influence of crystallization solvents and magnetic field intensity on the crystallization process of scopolamine hydrobromide, as well as the impact of magnetic field on the crystal growth direction, were investigated. The results revealed that treatment under magnetic field led to a shortened induction time (25.64–75.46%), an increased purity of crystals (0.95–2.92%), and an enhanced recovery rate (4.51–10.78%). Furthermore, it was also discovered that magnetic field could destroy hydrogen bonds within the solution, and change the physical properties of the mother liquid, so as to promote the nucleation formation and crystal growth. These findings suggested that external magnetic field could be a promising method for scopolamine preparation.
      Citation: Separations
      PubDate: 2023-09-14
      DOI: 10.3390/separations10090504
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 505: Enhanced CO2 Capture by Sorption on
           Electrospun Poly (Methyl Methacrylate)

    • Authors: Michele Ciulla, Valentino Canale, Rafal D. Wolicki, Serena Pilato, Pantaleone Bruni, Stefania Ferrari, Gabriella Siani, Antonella Fontana, Pietro Di Profio
      First page: 505
      Abstract: Poly(methyl methacrylate) (PMMA) is characterized by high CO2 capture yield under mild pressures and temperatures. A morphological modification of powdery amorphous PMMA (pPMMA) is carried out by electrospinning to increase the surface/volume ratio of the resulting electrospun PMMAs (ePMMAs). This modification improves the kinetics and the capture yields. The rate constants observed for ePMMAs are two to three times higher than those for pPMMA, reaching 90% saturation values within 5–7 s. The amount of sorbed CO2 is up to eleven times higher for ePMMAs at 1 °C, and the highest difference in captured CO2 amount is observed at the lowest tested pressure of 1 MPa. The operating life of the ePMMAs shows a 5% yield loss after ten consecutive runs, indicating good durability. Spent electrospun PMMAs after several cycles of CO2 sorption-desorption can be regenerated by melting and again electrospinning the molten mass, resulting in a CO2 capture performance that is undistinguishable from that observed with fresh ePMMA. Scanning electron and atomic force microscopies show a reduction in surface roughness after gas exposure, possibly due to the plasticization effect of CO2. This study shows the potential of electrospun PMMAs as solid sorbents for carbon capture from natural gas or pre-combustion and oxyfuel combustion processes.
      Citation: Separations
      PubDate: 2023-09-14
      DOI: 10.3390/separations10090505
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 506: Removal of Azo Dyes from Aqueous Effluent
           Using Bio-Based Activated Carbons: Toxicity Aspects and Environmental

    • Authors: Ahmed Elsayid Ali, Zaira Zaman Chowdhury, Ramprosad Devnath, Md. Mostak Ahmed, Md. Mahfujur Rahman, Khalisanni Khalid, Yasmin Abdul Wahab, Irfan Anjum Badruddin, Sarfaraz Kamangar, Mohamed Hussien, Khalid Husain Pallan, Ajita Mitra
      First page: 506
      Abstract: Rapid growth in various industrial fields has introduced a series of new environmental risks. The textile industry is one of the major industries that is influenced by rapid advancements in technological sectors. The development in textile dying technologies has presented new types of dyes that are toxic to the ecosystem. Azo dyes are the main artificial dyes used in textiles, food, and other applications. Typically, these dyes are introduced into the environment as wastewater discharged from factories. The discharged influence penetrates the ecosystem and causes deadly diseases to human and animals. Several studies present activated carbon as a proper solution to eliminating the presence of azo dyes in the environment. However, various types of azo dye have different properties and chemical structures. Thus, there is a crucial need for more studies on the application of activated carbons to eliminate the presence of azo dyes in the environment. This paper discusses the toxic effects of azo dyes on the environment and human health. Moreover, this work presents a general review of the preparation of activated carbon and the parameters that influence the adsorption performance.
      Citation: Separations
      PubDate: 2023-09-15
      DOI: 10.3390/separations10090506
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 507: Microalgae Biomass Harvesting Using
           Chitosan Flocculant: Optimization of Operating Parameters by Response
           Surface Methodology

    • Authors: Harun Elcik, Dogan Karadag, Ayse Irem Kara, Mehmet Cakmakci
      First page: 507
      Abstract: Bioflocculants can be used for cost-effective harvesting of microalgae biomass on an industrial scale. This study investigates the flocculation-based harvesting approach to recovering Chlorella vulgaris microalgae biomass using chitosan biopolymer. Response surface methodology (RSM) was used to design the experiments and optimize the critical operating parameters. Box-Behnken Design (BBD) was employed at three levels, and 17 experimental runs were conducted to determine the optimal conditions and the relationship between operating parameters. The highest biomass recovery of 99.10% was achieved at the following optimized conditions: pH of 5, flocculation time of 45 min, and chitosan concentration of 10 mg/L. Both experimental results and model outputs indicated that pH significantly impacts microalgae harvesting and that process performance is less dependent on chitosan concentration and flocculation time. The quadratic model has shown the best fit with the experimental results. The results could be applied to large-scale microalgae harvesting applications to promote microalgae biomass recovery and reduce operating costs.
      Citation: Separations
      PubDate: 2023-09-15
      DOI: 10.3390/separations10090507
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 508: The Simultaneous Determination of Nine
           Furocoumarins in Angelica dahurica Using UPLC Combined with the QAMS
           Approach and Novel Health Risk Assessment Based on the Toxic Equivalency

    • Authors: Zhao Wang, Ke Zan, Xiao-Wen Hu, Shuai Kang, Hai-Liang Li, Tian-Tian Zuo, Hong-Yu Jin, Shuang-Cheng Ma
      First page: 508
      Abstract: Objective: This study aimed to provide data for the type and content of linear furocoumarins (FCs) in Angelica dahurica (AD) in order to assess their cumulative risks and provide a scientific basis for the rational use and quality evaluation of the medicinal AD to improve public health. Methods: A UPLC method was developed for the simultaneous determination of nine FCs initially by using imperatorin (Im) as the internal standard substance, including Im, phellopterin (Ph), isoimperatorin (Is), oxypeucedanin hydrate (Oh), byakangelicin (Bn), xanthotoxin (8-MOP), bergapten (5-MOP), byakangelicol (Bl), and oxypeucedanin (Op) in two species of Angelica dahurica (AD). And, the risk assessment for the total FCs in AD was explored using the hazard index combined with the toxic equivalency factor (TEF-HI) strategy for the first time. Results: The established method revealed acceptable applicability, and there were no significant differences compared with the external standard method (ESM). The quantitative results demonstrated that the total content of FCs in Angelica dahurica (BZ) were higher than that in Angelica dahurica var. formosana (HBZ), and there was a great difference between the Bl and Op. Moreover, the risk assessment data revealed that the risk of total FCs in AD to human health was low. Conclusions: The established UPLC method that determined nine FCs in AD using a single marker could solve the problem of difficulty in obtaining a chemical reference substance with high purity and requiring a long determination time. And, the TEF-HI risk assessment approach associated with FCs in ADs could guide the rational utilization of toxic FCs in ADs in the progress of improving public health safety. In short, the whole systematic strategy provides a scientific basis for rational quality evaluation and the healthy use of related herbal medicines.
      Citation: Separations
      PubDate: 2023-09-15
      DOI: 10.3390/separations10090508
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 509: Enhancing Uranium Extraction Efficiency
           Using Protonated Amines and Quaternary Ammoniums-Based Ionic Liquids:
           Mechanistic Insights and Nonlinearities Analysis

    • Authors: Elise Guerinoni, Sandrine Dourdain, Thomas Dumas, Guilhem Arrachart, Fabrice Giusti, Zijun Lu, Pier-Lorenzo Solari, Stéphane Pellet-Rostaing
      First page: 509
      Abstract: This study investigates uranium solvent extraction under AMEX process conditions. The use of pure extractants without diluents or phase modifiers allows us not only to reduce the use of volatile organic compounds but also to provide higher extraction yields without third-phase formation. Pure extractants are protonated amines or quaternary ammoniums with suitable counter ions, which act at the interface between ion pairs and protic ionic liquids. The mixture of sulphates anion (SO42−) and bis(trifluoromethanesulfonyl)imide anion (NTf2−) revealed unexpected nonlinear extraction behaviors, which appear highly important to rationalize for optimized application. A spectroscopic analysis (NMR, UV-vis, FT-IR, and EXAFS) showed that uranium extraction occurs via a protonated amine and three sulphates. A nonlinear extraction could further be interpreted by considering a water and acid transfer between the two phases: at lower sulphate ratios, the release of acid from the organic phase into the aqueous phase was shown to influence the number of protonated amines in the organic phase, affecting uranium extraction before its enhancement. Furthermore, the extraction loss at higher sulphate ratios was assigned to the destabilization of bidentate uranium–sulphate complexes due to a competition between water and sulphates.
      Citation: Separations
      PubDate: 2023-09-15
      DOI: 10.3390/separations10090509
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 510: Extraction of Gallium from the Brown
           Corundum Dust with a One-Step Alkaline Leaching Process

    • Authors: Juhua Zhang, Cong Gao, Xujie Hui, Yuwei Chang
      First page: 510
      Abstract: Brown corundum dust, which is created during the manufacturing of brown corundum using bauxite as the raw material, is a vital carrier of gallium. To ascertain the presence of the contained gallium, the brown corundum dust was measured and characterized (XRF, XRD, ICP-OES, EPMA, SEM-EDS, etc.). Gallium was extracted from the brown corundum dust using a one-step alkali leaching process, and thermodynamic calculations were utilized to assess the viability of the leaching reactions. The effects of leaching parameters (NaOH solution concentration, leaching time, leaching temperature, solid–liquid ratio and stirring speed) on the recovery of gallium during the leaching process were investigated. A gallium recovery of 96.83% was discovered to be possible with the following parameters: 200 g/L of NaOH, 363 K for the leaching temperature, 60 min for the leaching time, 1:10 g/mL for the solid–liquid ratio, and 850 rpm for the stirring rate. Gallium extraction was negatively impacted by raising the leaching temperature above 363 K and the concentration of NaOH solution above 200 g/L due to the accelerated side reactions between Na+, K+, SiO44− and AlO2−, which led to the precipitation of aluminosilicates that absorbed gallium from the solution. The influences of leaching parameters such as the temperature, NaOH solution concentration, and solid–liquid ratio on the leaching kinetics were examined. It was demonstrated that the leaching process followed the unreacted shrinking core model, that the interfacial diffusion associated with the contacting surface area served as the controlling step, and that the apparent activation energy was 42.83 kJ/mol. It turned out that the final kinetic equation was 1/(1 − α)1/3 − 1 = 4.34 × 104 × (CNaOH)2.12 (L/S)0.43exp[−42835/(RT)] t.
      Citation: Separations
      PubDate: 2023-09-15
      DOI: 10.3390/separations10090510
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 511: Optimized Apparatus Design for Continuous
           Aqueous Two-Phase Flotation (ATPF)

    • Authors: Lucas Jakob, Helene Katharina Baust, Lukas Griesinger, Hermann Nirschl
      First page: 511
      Abstract: Aqueous two-phase flotation (ATPF) is an integrative downstream method for separating and concentrating biomolecules from crude biosuspensions such as fermentation broth. Its continuous operation not only increases throughput, but also makes it recommended for continuous upstreams. In this work, an optimized apparatus design in the form of a horizontal flotation tank is presented. The geometry of the new apparatus for continuous ATPF is optimized using flow simulations so that the two aqueous phases can be pumped uniformly through the flotation tank in co-current or counter-current flow. The implementation of a conductivity measurement enables to characterize the phase mixing effect induced by the rising gas bubbles introduced through three different gassing units. ATPF experiments with the model enzyme phospholipase A2 show that there are favorable combinations of gas flow rates to increase the flotation rate and reduce the back-diffusion at the outlet of the apparatus. This allows high phase exchange rates up to 2/h and hence increases the amount of enzymes that can be recovered per time. Co-current operation of continuous ATPF increased separation efficiency about 14% up to E = 74% compared to counter-current operation.
      Citation: Separations
      PubDate: 2023-09-16
      DOI: 10.3390/separations10090511
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 512: An Experimental Investigation of the
           Influence of High-Frequency Standing Sound Waves on Depth Filtration Using
           Coarse-Pored Media

    • Authors: Jonas Hasenkrug, Rouven Schweitzer
      First page: 512
      Abstract: When a suspension passes through a high-frequency standing sound wave, the particles it contains are manipulated by acoustic forces. In a one-dimensional sound field, these forces lead to a planar arrangement of the particles and the formation of agglomerates. It is known that the combination of these forces and depth filtration can be utilized to significantly increase the filter efficiency of coarse-pored media. So far, this concept has only been used in microfluidics. In this paper, we present the results of a scaled-up filtration channel to test the viability of the industrial application of acoustically assisted filtration systems for the removal of microparticles. The influences of acoustic power input, flow rate, and the porosity of the filter media are investigated. In addition to verifying the scalability, a significant decrease in the large particle fraction in the outflow of the channel was observed when a high-power sound field is applied. Furthermore, the formed agglomerates tend to rise to the fluid surface. The floating particles mostly consist of a large particle fraction.
      Citation: Separations
      PubDate: 2023-09-16
      DOI: 10.3390/separations10090512
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 513: Photocatalytic Removal of Crystal Violet
           Dye Utilizing Greenly Synthesized Iron Oxide Nanoparticles

    • Authors: Mohamed Taha Yassin, Fatimah O. Al-Otibi, Abdulaziz A. Al-Askar
      First page: 513
      Abstract: The presence of synthetic industrial dyes in the environment poses significant risks to aquatic ecosystems, human health, and economies. This study aims to synthesize iron oxide nanoparticles (IONPs) using a green method, analyze them using physicochemical techniques, and examine the effectiveness with which they photocatalytically degrade crystal violet dye in sunlight. Fourier transform infrared spectroscopy (FTIR) analysis revealed that the biogenic IONPs showed a UV peak at a wavelength of 241 nm, with functional groups including phenols, alkynes, and alkenes. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the bioinspired IONPs. The mean diameter of the biogenic IONPs was 49.63 ± 9.23 nm, and they had a surface charge of −5.69 mV. The efficiency with which the synthesized IONPs removed the crystal violet dye was evaluated under dark and sunlight conditions. The removal efficiency was found to be concentration and time dependent, with a peak removal percentage of 99.23% being achieved when the IONPs were exposed to sunlight for 210 min. The biogenic IONPs also demonstrated antioxidant activity, with a relative IC50 value of 64.31 µg/mL. In conclusion, biogenic IONPs offer a viable and environmentally friendly approach for eradicating industrial synthetic dyes and remediating contaminated environments and aquatic ecosystems.
      Citation: Separations
      PubDate: 2023-09-17
      DOI: 10.3390/separations10090513
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 514: Impact of Cumin and Green Tea on
           Amlodipine Pharmacodynamics and Pharmacokinetics in Hypertensive Rats

    • Authors: Ibrahim Abdelsalam Abdelrahman, Abdul Ahad, Mohammad Raish, Yousef A. Bin Jardan, Mohd Aftab Alam, Fahad I. Al-Jenoobi
      First page: 514
      Abstract: The main purpose of the current research was to determine the impact of cumin and green tea on the pharmacodynamics and pharmacokinetics of amlodipine in hypertensive rats. Wistar rats were given 40 mg/kg of L-NAME orally every day for two weeks in order to induce hypertension. The groups treated with herbs received L-NAME with a daily oral dose of cumin (200 mg/kg) and green tea (200 mg/kg), respectively. After the treatment for 14 days, blood pressure was measured at specific intervals using a tail-cuff BP-measurement device for 24 h. For oral pharmacokinetics of amlodipine (single dose, 1 mg/kg), the blood samples were collected at predetermined intervals up to 24 h, and plasma samples were analyzed using UPLC-LC MS/MS. In comparison to the hypertensive control group, green tea and cumin significantly decreased systolic and diastolic blood pressures, as well as mean arterial pressures. Green tea has demonstrated a more prominent effect on pharmacodynamic of amlodipine compared to cumin. The rats treated with amlodipine, cumin + amlodipine, and green tea + amlodipine exhibited AUC0-t of 38.85 ± 14.8 ng h/mL, 52.05 ± 10.2 ng h/mL, and 114.73 ± 24.94 ng h/mL, respectively. In addition, it has been observed that co-administration of green tea and cumin increases the Cmax and T1/2 of amlodipine. The results indicated a potential interaction between amlodipine and the investigated herbs in hypertensive rats. Hence, precautions should be taken while concurrently administrating amlodipine with the investigated herbs.
      Citation: Separations
      PubDate: 2023-09-18
      DOI: 10.3390/separations10090514
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 515: An Ultra-Fast and Green LC-MS Method for
           Quantitative Analysis of Aesculin and Aesculetin in Cortex Fraxini

    • Authors: Xiaodong Wang, Wenhao Wang, Qinggui Lei, Zhengming Qian, Wenbin Deng
      First page: 515
      Abstract: This study aims to develop a fast and eco-friendly liquid chromatography–mass spectrometry (LC-MS) method for the determination of aesculin and aesculetin in Cortex Fraxini. Ultrapure water was used as the solvent during the microwave-assisted extraction process to prepare the Cortex Fraxini sample. This extraction method reduces the cost of the harmful solvent (only ultrapure water was used) and microwave extraction time (1 min). The LC separation was conducted using an Agilent InfinityLab Poroshell 120 EC-C18 column (2.1 mm × 30 mm, 2.7 µm) with a mobile phase consisting of 0.1% formic acid and acetonitrile (90:10, v/v) at a flow rate of 0.6 mL/min. Isocratic elution was employed, and the analytes were detected by MS. Through careful optimization and selection of LC-MS conditions, the analysis time was reduced to 1 min, demonstrating the method’s efficiency. The developed method was validated and exhibited excellent specificity, linearity, limit, precision, accuracy, and stability in quantifying aesculin and aesculetin in the Cortex Fraxini samples. The analysis result revealed the presence of aesculin (ranging from 3.55 to 18.8 mg/g) and aesculetin (ranging from 1.01 to 16.2 mg/g) in all ten batches of Cortex Fraxini samples. Compared to the reported LC methods, this approach substantially reduces the total analysis time and requires a minuscule volume of organic solvents. An “Analytical Eco-Scale” assessment was used to evaluate the different assay methods of Cortex Fraxini. The current LC-MS method scored an impressive 90; it was better than the other four reports’ LC methods. Thus, the developed LC-MS method is rapid and green, which is helpful for the quality evaluation of Cortex Fraxini.
      Citation: Separations
      PubDate: 2023-09-19
      DOI: 10.3390/separations10090515
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 516: Organic Solvent Nanofiltration and
           Data-Driven Approaches

    • Authors: Pieter-Jan Piccard, Pedro Borges, Bart Cleuren, Jef Hooyberghs, Anita Buekenhoudt
      First page: 516
      Abstract: Organic solvent nanofiltration (OSN) is a membrane separation method that has gained much interest due to its promising ability to offer an energy-lean alternative for traditional thermal separation methods. Industrial acceptance, however, is held back by the slow process of membrane screening based on trial and error for each solute-solvent couple to be separated. Such time-consuming screening is necessary due to the absence of predictive models, caused by a lack of fundamental understanding of the complex separation mechanism complicated by the wide variety of solute and solvent properties, and the importance of all mutual solute-solvent-membrane affinities and competing interactions. Recently, data-driven approaches have gained a lot of attention due to their unprecedented predictive power, significantly outperforming traditional mechanistic models. In this review, we give an overview of both mechanistic models and the recent advances in data-driven modeling. In addition to other reviews, we want to emphasize the coherence of all mechanistic models and discuss their relevance in an increasingly data-driven field. We reflect on the use of data in the field of OSN and its compliance with the FAIR principles, and we give an overview of the state of the art of data-driven models in OSN. The review can serve as inspiration for any further modeling activities, both mechanistic and data-driven, in the field.
      Citation: Separations
      PubDate: 2023-09-19
      DOI: 10.3390/separations10090516
      Issue No: Vol. 10, No. 9 (2023)
  • Separations, Vol. 10, Pages 419: Separation Science and Technology for
           Environmental Applications

    • Authors: Dimosthenis L. Giokas
      First page: 419
      Abstract: One of the driving forces behind the significant advancements in environmental separation science is the need for creative solutions to the evolving environmental challenges. [...]
      Citation: Separations
      PubDate: 2023-07-25
      DOI: 10.3390/separations10080419
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 420: GC-MS Analysis and Bioactivity Screening
           of Leaves and Fruits of Zanthoxylum armatum DC.

    • Authors: Jie Ma, Liping Ning, Jingyan Wang, Wei Gong, Yue Gao, Mei Li
      First page: 420
      Abstract: Zanthoxylum armatum DC. is a plant that has been homologated for medicine and food by the Chinese for three thousand years. In this study, the essential oils of fresh leaves and fruits were extracted by hydrodistillation, the aromas of fresh leaves and fruits were extracted by headspace solid-phase microextraction and their chemical compositions were analyzed by gas chromatography mass spectrometry. The main components of the leaf essential oils were linalool (62.01%), 2-undecanone (9.83%) and 2-tridecanone (5.47%); the fruit essential oils were linalool (72.17%), limonene (8.05%) and sabinene (6.77%); the leaf aromas were limonene (39.15%), β-myrcene (15.8%), sabinene (8.17%) and linalool (5.25%); the fruit aromas were limonene (28.43%), sabinene (13.56%), linalool (11.47%) and β-myrcene (8.64%). By comparison, it was found that the composition of leaf essential oils and fruit essential oils were dominated by oxygenated monoterpenes, while the composition of their aromas were both dominated by monoterpenes; the relative content of non-terpene components in leaf essential oil and leaf aroma is second only to oxygenated monoterpenes, while their content in fruits is low; the chemical composition of leaf aromas and fruit aromas were richer than those of essential oils. In this study, we reported for the first time that the antitumor, tyrosinase inhibition, HMGR inhibition and nitric oxide production inhibition activity of leaf essential oils were stronger than those of fruit essential oils in in vitro tests. The results of the study can provide a reference for the recycling and green low-carbon transformation of the leaves, and also help to deepen the understanding of the value of the volatile chemical constituents of this plant in “forest medicine” or “aromatherapy”, and provide new ideas for the transformation of the value of the plant in the secondary and tertiary industry chain.
      Citation: Separations
      PubDate: 2023-07-25
      DOI: 10.3390/separations10080420
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 421: Phytochemical Profile, Antioxidant
           Activity and Cholinesterase Inhibition Potential of Essential Oil and
           Extracts of Teucrium montanum from Bosnia and Herzegovina

    • Authors: Mejra Bektasevic, Mladenka Jurin, Marin Roje, Olivera Politeo
      First page: 421
      Abstract: Bioactive compounds from plants play an important role in slowing many neurodegenerative diseases, such as Alzheimer’s disease, by inhibiting cholinesterase enzymes. Studies have shown that oxidative stress is associated with the development of Alzheimer’s disease. In traditional medicine of Bosnia and Herzegovina, Teucrium montanum is used to treat numerous diseases. The chemical composition and biological activity of the essential oil (EO) and aqueous (AE) and methanol extract (ME) of this plant were studied. The chemical composition of EO was studied using GC-MS, while the composition of the extracts was studied using HPLC-DAD. Antioxidant activity was tested using the DPPH and FRAP methods. The protection of lipids and proteins from oxidation was tested using the ammonium thiocyanate and BSA oxidation methods. The ability to inhibit cholinesterases was tested by the Ellman method. The main identified EO compounds were α-cadinol, ß-selinene, δ-cadinene, epi-α-cadinol, germacrene D-4-ol, and α-pinene. The main phenolic compounds of the extracts were p-coumaric acid, ellagic acid and caffeic acid. The tested extracts showed good antioxidant radical scavenging and reducing potential and a very good ability to protect lipids and proteins from oxidation. The EO showed moderate AChE and BChE inhibition potential, while the extracts showed weak or no ability.
      Citation: Separations
      PubDate: 2023-07-26
      DOI: 10.3390/separations10080421
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 422: Adsorption of Phenols on Carbonaceous
           Materials of Various Origins but of Similar Specific Surface Areas

    • Authors: Krzysztof Kuśmierek, Andrzej Świątkowski
      First page: 422
      Abstract: The adsorption of phenol (Ph), 4-chlorophenol (CP), and 4-cresol (MP) from aqueous solutions on three carbonaceous materials of diverse origins but similar specific surface areas was investigated. Vulcan XC72 carbon black (CB), AKP-5 activated coke (AC), and activated tire pyrolysis char (AP) were examined as adsorbents. The kinetics and equilibrium adsorption, as well as the influence of pH and ionic strength of each solution on the adsorption process, were studied. The results revealed that the adsorption was pH-dependent and preferred an acidic environment. The presence of an inorganic salt in the solution (ionic strength) did not affect the adsorption processes of the three adsorbates. The pseudo-first- and pseudo-second-order equations, as well as the Weber–Morris and Boyd kinetic models, were used to describe the adsorption kinetics. It was found that equilibrium was reached for all adsorbates after approximately 2–3 h. Adsorption kinetics followed a pseudo-second-order model, and the adsorption rate was determined by film diffusion. The adsorption isotherms were described using the Langmuir and Freundlich equations. The results revealed that the adsorption processes of Ph, CP, and MP on all three adsorbents from the water were better described by the Langmuir model. The adsorption of CP was the most efficient, the adsorption of MP was slightly weaker, and the adsorption of phenol was the least efficient.
      Citation: Separations
      PubDate: 2023-07-26
      DOI: 10.3390/separations10080422
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 423: A Novel UHPLC-MS/MS-Based Bioanalytical
           Method Developed for S-Allyl Cysteine in the Establishment of a
           Comparative Pharmacokinetic Study

    • Authors: Mohd Faiyaz Khan, Niyaz Ahmad, Faisal K. Alkholifi, Zabih Ullah, Sadaf Farooqui, Nazia Khan, Mohammed Saifuddin Khalid, Mir Naiman Ali, Hajera Tabassum
      First page: 423
      Abstract: A newly UHPLC-MS/MS method development and validation for S-Allyl Cysteine was used to evaluate the comparative pharmacokinetic parameters. SC PLGA NPs (S-Allyl Cysteine Poly (D,L-lactide-co-glycolic acid) Nanoparticles) were developed by the emulsion solvent evaporation method. SC PLGA NPs showed their drug loading and encapsulation efficiency to be 5.13 ± 0.10% and 82.36 ± 4.01%, respectively. SC PLGA NPs showed a spherical morphology of an average size (134.8 ± 4.61 nm), PDI: 0.277 ± 0.004, and −25.3 ± 1.03 mV Zeta-Potential (ZP), and is suitable for oral delivery. The development and validation of the UHPLC-MS/MS bioanalytical method were performed successfully for PK-parameter examinations with 1.219 min RT, MS (162.00/73.10), and a total run-time of 2.0 min. Additionally, 1.0–1000.0 ng/mL was a linear range with inter- and intra-day accuracy of 92.55–99.40%, followed by a precision of 1.88–4.23%. SC PLGA NP’s oral bioavailability was significantly higher (** p < 0.01) in comparison to the SC-S treated groups’ (iv and oral). The antimicrobial activity of SC PLGA NPs proved to be more effective than pure S-Allyl-L-Cysteine with significant results (p < 0.01) in comparison to SC-S. SC PLGA NPs showed fitted physicochemical and enhanced antimicrobial properties, which can be helpful for oral administration. Based on the proposed research results, SC PLGA NPs were used for the improvement in oral bioavailability with a sustained and controlled release of S-Allyl-L-Cysteine delivery.
      Citation: Separations
      PubDate: 2023-07-26
      DOI: 10.3390/separations10080423
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 424: Commercial Anion Exchange Membranes
           (AEMs) for Fuel Cell and Water Electrolyzer Applications: Performance,
           Durability, and Materials Advancement

    • Authors: Wei Keat Ng, Wai Yin Wong, Nur Adiera Hanna Rosli, Kee Shyuan Loh
      First page: 424
      Abstract: The utilization of anion exchange membranes (AEMs) has revolutionized the field of electrochemical applications, particularly in water electrolysis and fuel cells. This review paper provides a comprehensive analysis of recent studies conducted on various commercial AEMs, including FAA3-50, Sustainion, Aemion™, XION Composite, and PiperION™ membranes, with a focus on their performance and durability in AEM water electrolysis (AEMWE) and AEM fuel cells (AEMFCs). The discussed studies highlight the exceptional potential of these membranes in achieving high current densities, stable operation, and extended durability. Furthermore, the integration of innovative catalysts, such as nitrogen-doped graphene and Raney nickel, has demonstrated significant improvements in performance. Additionally, the exploration of PGM-free catalysts, such as Ag/C, for AEMFC cathodes has unveiled promising prospects for cost-effective and sustainable fuel cell systems. Future research directions are identified, encompassing the optimization of membrane properties, investigation of alternative catalyst materials, and assessment of performance under diverse operating conditions. The findings underscore the versatility and suitability of these commercial AEMs in water electrolysis and fuel cell applications, paving the way for the advancement of efficient and environmentally benign energy technologies. This review paper serves as a valuable resource for researchers, engineers, and industry professionals seeking to enhance the performance and durability of AEMs in various electrochemical applications.
      Citation: Separations
      PubDate: 2023-07-26
      DOI: 10.3390/separations10080424
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 425: Effects of Dissolved Organic Matter on
           the Release of Soluble Phosphorus and Fluoride Ion from Phosphate Ore

    • Authors: Fengjiao Zhang, Huaying Liu, Yanqiong Ma, Yingjie Li, Cheng Tie, Qilin Zhao
      First page: 425
      Abstract: Unreasonable storage of phosphate ore is becoming an important pathway causing phosphate pollution in the surrounding aquatic environment. However, there is little research on the influence of dissolved organic matter (DOM) in water on the fate of phosphate ore. Here, we collected phosphate ores from two phosphate mines along the coast of Tanglang River and studied the effects of DOM concentrations and pH on the release of soluble active phosphorus (SRP) and fluoride ion (F−) from phosphate ores using humic acid (HA) as the representative of DOM. Based on the analysis of ZP, FTIR, XPS, and SEM, the influence mechanism of HA was revealed. The results showed that HA efficiently promoted the release of SRP and F− from phosphate ore. With decreasing pH, the P release increased in both water and HA solutions in general. The beneficial influence of HA on the release of SRP and F− from phosphate ore was ascribed to the introduction of oxygen-containing functional groups by HA, which altered the surface properties and enhanced the dispersion stability of phosphate ore. These findings provided new insights into the dispersion behavior of phosphate ore, which is helpful in promoting the pollution control and management strategy of phosphate ore.
      Citation: Separations
      PubDate: 2023-07-27
      DOI: 10.3390/separations10080425
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 426: Removal of Azo Dyes Orange II and
           Reactive Black 5 from Aqueous Solutions by Adsorption on Chitosan Beads
           Modified with Choline Chloride: Urea Deep Eutectic Solvent and FeO

    • Authors: Óscar Martínez-Rico, Lucía Blanco, Ángeles Domínguez, Begoña González
      First page: 426
      Abstract: The removal of the azo dyes Orange II (OII) and Reactive Black 5 (RB5) from aqueous solutions was studied using three types of adsorbents derived from chitosan: unmodified chitosan beads (un-Ch), chitosan beads tuned with a deep eutectic solvent (DES) composed of choline chloride:urea at a 1:2 molar ratio (Ch-DES), along with FeO nanoparticles added to chitosan and modified with DES (Ch-FeO-DES). Both dyes were effectively removed in 3–4 h when Ch-DES beads were used, at a dye concentration range of 25–50 mg/L. The modification with DES improved the removal efficiency to achieve increases of around 32% for OII and 17% for RB5. The adsorbent dosage and the initial dye concentration influenced the adsorption process. Isotherm adsorption models (Langmuir, Freundlich, and Temkin) and kinetic models (pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models) were applied to identify the adsorption behavior. The process could be characterized by employing the pseudo-second-order kinetic model and fitting it to the monolayer Langmuir isotherm. The adsorption occurred on a monolayer with no interaction among dye molecules when electrostatic forces would determine the attaching of dye molecules on the adsorbent. OII was efficiently desorbed by an alkaline solution, while RB5 was more strongly attached. The adsorbent could be recycled, after regeneration with an acid solution, for at least 5 reuse cycles while still achieving effective OII removal. Reactivation with a diluted EDTA solution allowed the authors to recycle RB5-attached beads, achieving optimum removal in two further uses.
      Citation: Separations
      PubDate: 2023-07-27
      DOI: 10.3390/separations10080426
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 427: Biosynthesis of
           Salbutamol-4′-O-sulfate as Reference for Identification of Intake
           Routes and Enantiopure Salbutamol Administration by Achiral UHPLC-MS/MS

    • Authors: Annika Lisa Jendretzki, Lukas Corbinian Harps, Yanan Sun, Felix Bredendiek, Matthias Bureik, Ulrich Girreser, Xavier de la Torre, Francesco M. Botrè, Maria Kristina Parr
      First page: 427
      Abstract: The aim of the study was a comprehensive and quantitative determination of salbutamol and its sulfoconjugated major metabolite in urine samples using achiral ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Therefore, salbutamol-4′-O-sulfate was biosynthesized as a reference using genetically modified fission yeast cells, and the product was subsequently characterized by NMR and HRMS. In competitive sports, salbutamol is classified as a prohibited drug; however, inhalation at therapeutic doses is permitted with a maximum allowance of 600 µg/8 h. In contrast, the enantiopure levosalbutamol is prohibited under any condition. For analytical discrimination, the amount of salbutamol and its main metabolite excreted in the urine was studied. As proof of concept, a longitudinal study in one healthy volunteer was performed in order to investigate excreted amounts and to study potential discrimination using achiral chromatography. Discrimination of administration of racemic salbutamol or the enantiopure levosalbutamol was not achieved by solely analyzing salbutamol as the parent compound. However, a distinction was possible by evaluation of the proportion of salbutamol-4′-O-sulfate in relation to salbutamol. Therefore, reference material of metabolites is of great importance in doping control, especially for threshold substances.
      Citation: Separations
      PubDate: 2023-07-28
      DOI: 10.3390/separations10080427
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 428: Isolation and Structural Elucidation of
           Unreported Prenylhydroquinone Glycoside from Sedum kamtschaticum Leaves
           and Its Effect on Hyperphosphorylated Tau Production in
           Aβ1–42-Treated SH-SY5Y Cells

    • Authors: Seung-Eun Lee, Se Yun Jeong, Yoon Seo Jang, Kwang-Jin Cho, Jeonghoon Lee, Yunji Lee, Ki Hyun Kim
      First page: 428
      Abstract: Sedum kamtschaticum Fischer, of the Crassulaceae family, is a perennial and medicinal plant used in Asian folk medicine to alleviate inflammatory disease and improve blood circulation. As part of our ongoing exploration into natural products, seeking to identifying bioactive compounds, we characterized, identified, and isolated an unreported bioactive compound, prenylhydroquinone glycoside (1), which we named kirinchoside from S. kamtschaticum leaves. Using high-resolution (HR)-ESIMS, NMR spectroscopic data, and enzymatic hydrolysis, followed by LC–MS analysis, we determined the structure of this isolated compound. Despite a previous report on the planar structure of compound 1 (kirinchoside), the absolute configuration of 1 had not been verified. We investigated the effects of kirinchoside on hyperphosphorylated tau (p-tau) accumulation, a hallmark of Alzheimer’s disease (AD) progression. We observed that treatment with 5 μM kirinchoside suppressed p-tau levels by 16.9% in amyloid β (Aβ)1–42-treated SH-SY5Y cells, compared to the negative control. These findings indicate that kirinchoside, an unreported prenylhydroquinone glycoside found in S. kamtschaticum leaves, could be a candidate preventive agent against AD via inhibition of p-tau accumulation.
      Citation: Separations
      PubDate: 2023-07-28
      DOI: 10.3390/separations10080428
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 429: Determination of β2-Agonist Residues
           in Meat Samples by Gas Chromatography-Mass Spectrometry with N-Doped
           Carbon Dots in Molecular Sieves

    • Authors: Shanshan Zhu, Binglin Mou, Liao Zheng, Luhong Wen, Ning Gan, Lin Zheng
      First page: 429
      Abstract: A simple, effective, and highly sensitive analytical approach was created and applied in this study for the accurate measurement of three β2-agonist residues (clenbuterol, salbutamol, and ractopamine) in meat samples. In the course of the experiment, new adsorbent molecular sieves (ZMS)@nitrogen-doped carbon quantum dots (N-CQDs) composite materials were synthesized with the aid of hydrothermal synthesis. The composite adsorbent materials were prepared and characterized through scanning electron microscopy, transmission electron microscope, X-ray photoelectron spectroscopy, fluorescence, and zeta potential. Four determinants affecting the extraction and elution’s efficiency, such as the amount of adsorbent, the extraction time, desorption time, and the amount of extraction salt, were substantially optimized. The analytes were quantified by gas chromatography–mass spectrometry. Final results of the methodological validation reflected that the ZMS@N-CQDs composite materials were able to adsorb three β2-agonist residues well and had good reproducibility. In the meantime, all analytes indicated good linearity with coefficient of determination R2 ≥ 0.9908. The limit of detection was 0.7–2.0 ng·g−1, the limit of quantification varied from 2.4 to 5.0 ng·g−1, the precision was lower than 11.9%, and the spiked recoveries were in the range of 79.5–97.8%. To sum up, the proposed approach was quite effective, reliable, and convenient for the simultaneous analysis of multiple β2-agonist residues. Consequently, this kind of approach was successfully applied for the analysis of such compounds in meat samples.
      Citation: Separations
      PubDate: 2023-07-28
      DOI: 10.3390/separations10080429
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 430: Superior Removal of Toxic Cr(VI) from
           Wastewaters by Natural Pine Bark

    • Authors: Yang, Kim, Park
      First page: 430
      Abstract: Hexavalent chromium (Cr(VI)) is one of the most toxic heavy metals found in industrial wastewater, so many researchers are working to develop efficient and environmentally friendly removal methods. It has been reported that natural biomass and its derivatives can be used to treat wastewaters containing Cr(VI). However, biomass with sufficient Cr(VI) removal performance to replace the existing chemical method, which is cheap and simple, has not been reported yet. This study reports that inexpensive, abundant, and commercially available pine bark has the highest Cr(VI) removal capacity (i.e., 376.3 mg/g) compared to biomass reported elsewhere. This value is six times higher than the theoretical value of an inorganic reducing agent (iron(II) sulfate heptahydrate). The main mechanism of Cr(VI) removal by pine bark was clearly identified through kinetic experiments, Fourier-transform infrared spectrometer, and X-ray photoelectron spectroscopy analyses, which were used to study the compositions, functional groups, and bonding states of pine bark. It was found that pine bark consists of various acidic functional groups that can act as electron donors to promote the removal of Cr(VI) through redox reactions. In conclusion, pine bark may be a promising candidate for the removal of Cr(VI) from wastewater, owing to its excellent removal capacity.
      Citation: Separations
      PubDate: 2023-07-28
      DOI: 10.3390/separations10080430
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 431: Separation of (2E,4E)-deca-2,4-dienal
           from a Biocatalytic Reaction Mixture Using Hydrophobic Adsorbents

    • Authors: Marta Ostrihoňová, Monika Antošová, Hana Dobiašová, Justína Čuchorová, Kvetoslava Vranková, Milan Polakovič
      First page: 431
      Abstract: Biocatalytic oxidation of a fatty acid preparation by enzymes released from a plant extract provided (2E,4E)-deca-2,4-dienal (2,4-DDAL), a valuable natural aroma. The post-reaction mixture contained several other compounds, from which 2,4-DDAL must be recovered. These included the main by-product trans-2-hexenal (2-HAL) and the unreacted substrate composed mainly of linoleic, palmitic, and oleic acids. The adsorption capacity and selectivity of 17 hydrophobic adsorbents were examined in batch equilibrium experiments. The highest binding capacity for 2,4-DDAL was around 30 mg/g. Due to a large excess of fatty acids in the mixture, the total adsorbed amounts of other components analyzed reached the values up to 150 mg/g. In addition, 2-HAL was always adsorbed more strongly than 2,4-DDAL, whereas fatty acids were mostly not adsorbed as effectively. The best-performing adsorbent, AmberLite FPX66, had a selectivity ratio of 6 for 2,4-DDAL with respect to the key impurity and linoleic acid. Ethanol, isopropanol, and acetone were examined as potential desorbents using batch adsorption experiments on AmberLite FPX66 from 2,4-DDAL solutions in organic solvents. Ethanol was found to be the best choice. Based on the batch equilibrium data, a column elution experiment was performed to purify 2,4-DDAL from the biocatalytic reaction mixture using elution with 96% ethanol.
      Citation: Separations
      PubDate: 2023-07-29
      DOI: 10.3390/separations10080431
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 432: Study of Estimated Ultimate Recovery
           Prediction and Multi-Stage Supercharging Technology for Shale Gas Wells

    • Authors: Yanli Luo, Jianying Yang, Man Chen, Liu Yang, Hao Peng, Jinyuan Liang, Liming Zhang
      First page: 432
      Abstract: The development of shale gas reservoirs often involves the utilization of horizontal well segmental multi-stage fracturing techniques. However, these reservoirs face challenges, such as rapid initial wellhead pressure and production decline, leading to extended periods of low-pressure production. To address these issues and enhance the production during the low-pressure stage, pressurized mining is considered as an effective measure. Determining the appropriate pressurization target and method for the shale gas wells is of great practical significance for ensuring stable production in shale gas fields. This study takes into account the current development status of shale gas fields and proposes a three-stage pressurization process. The process involves primary supercharging at the center station of the block, secondary supercharging at the gas collecting station, and the introduction of a small booster device located behind the platform separator and in front of the outbound valve group. By incorporating a compressor, the wellhead pressure can be reduced to 0.4 MPa, resulting in a daily output of 12,000 to 14,000 cubic meters from the platform. Using a critical liquid-carrying model for shale gas horizontal wells, this study demonstrates that reducing the wellhead pressure decreases the critical flow of liquid, thereby facilitating the discharge of the accumulated fluid from the gas well. Additionally, the formation pressure of shale gas wells is estimated using the mass balance method. This study calculates the cumulative production of different IPR curves based on the formation pressure. It develops a dynamic production decline model for gas outlet wells and establishes a relationship between the pressure depletion of gas reservoirs and the cumulative gas production before and after pressurization of H10−2 and H10−3 wells. The final estimated ultimate recovery of two wells is calculated. In conclusion, the implementation of multi-stage pressurization, as proposed in this study, effectively enhances the production of, and holds practical significance for, stable development of shale gas fields.
      Citation: Separations
      PubDate: 2023-07-29
      DOI: 10.3390/separations10080432
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 433: Water-Based Microwave-Assisted Extraction
           of Pigments from Madder Optimized by a Box–Behnken Design

    • Authors: Marine Chambaud, Cyril Colas, Emilie Destandau
      First page: 433
      Abstract: Water is one of the greenest and most accessible solvents. To harness its potential, the water-based microwave-assisted extraction (MAE) of pigments from madder was optimized by the response surface methodology (RSM) using a Box–Behnken experimental design. The extract that presented both the highest extraction yield and the most intense color was obtained after a 30-s cycle at 1000 W using 100 mg of madder for 20 mL of water. This water-based MAE was more efficient than Soxhlet extraction and proved comparable to hydroalcoholic MAE. The optimized extract was further characterized using UHPLC-HRMS/MS to identify its main compounds. Glycosylated flavonoids and anthraquinones were putatively identified, as well as free anthraquinones, generally found in madder. The microwave-assisted extraction extended the range of polarity of the extracted compounds, making the water more versatile.
      Citation: Separations
      PubDate: 2023-07-30
      DOI: 10.3390/separations10080433
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 434: Screening and Experimental Validation for
           Selection of Open Metal Sites Metal-Organic Framework (M-CPO-27, M = Co,
           Mg, Ni and Zn) to Capture CO2

    • Authors: Nor Ernie Fatriyah Kari, Marhaina Ismail, Aqeel Ahmad, Khaliesah Kamal, Thiam Leng Chew, Mohamad Azmi Bustam
      First page: 434
      Abstract: The release of CO2 into the atmosphere has become a primary issue nowadays. Recently, researchers found Metal-Organic Frameworks M-CPO-27 (M = Mg, Co, Ni, and Zn) to be revolutionary for CO2 adsorption due to the presence of open metal sites enhancing CO2 binding and leading to higher capacity. This study aims to select the best metal center for CPO-27 with the high performance of CO2 adsorption by screening metal centers using simulation as a preliminary selection method. Then, the different metal centers were synthesized using the solvothermal process for validation. The synthesis of MOFs is confirmed through PXRD and FTIR analysis. Subsequently, by using simulation and experimental methods, it is discovered that Ni-CPO-27 gives the best performance compared with magnesium, zinc, and cobalt metal centers. The CO2 adsorption capacity of synthesized Ni-CPO-27 is 5.6 mmol/g, which is almost 20% higher than other MOFs. In conclusion, the prospective outcome of changing the metal from Mg-CPO-27 to Ni-CPO-27 would be advantageous in this investigation owing to its excellent performance in capturing CO2.
      Citation: Separations
      PubDate: 2023-08-01
      DOI: 10.3390/separations10080434
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 435: Isolation of Osteoblastic
           Differentiation-Inducing Constituents from Peanut Sprouts and Development
           of Optimal Extraction Method

    • Authors: Eun-Sang Cho, Chung Hyeon Lee, Min Sung Ko, Jee Yeon Choi, Kwang Woo Hwang, So-Young Park
      First page: 435
      Abstract: Osteoporosis, one of the most common bone diseases, results from an imbalance between bone formation and resorption. Osteoblasts are primarily involved in bone formation, whereas osteoclasts are involved in bone resorption. Therefore, any substances that can increase osteoblastic differentiation would be beneficial for the prevention or treatment of osteoporosis. In this study, peanut sprouts, a germinated product of peanuts, significantly enhanced osteoblastic differentiation of pre-osteoblastic MC3T3-E1 cells, as determined by the alkaline phosphatase (ALP) assay. The ethyl acetate fraction of peanut sprout extract was subjected to diverse column chromatographies using silica gel, ODS, and Sephadex LH-20 as stationary phases, and three nucleobases, namely, adenine, uracil, and thymine, and three phenolic acids, including caffeic acid, coumaric acid, and ferulic acid, were isolated as active constituents. In particular, adenine at 4 μg/mL and caffeic acid at 1 μg/mL increased ALP activity by 40 and 30%, respectively, compared with the osteoblastic differentiation medium-treated group, and these two compounds were set as marker compounds. Furthermore, extraction of peanut sprouts grown for 14–17 days with 60% ethanol was the best condition to obtain a high quantity of extract for peanut sprouts by analyzing the contents of marker compounds through HPLC. Together, these results suggest that peanut sprouts and their isolated compounds significantly enhance osteoblastic differentiation. Therefore, peanut sprouts have the potential to be developed as functional foods against osteoporosis.
      Citation: Separations
      PubDate: 2023-08-01
      DOI: 10.3390/separations10080435
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 436: Chemometric Approach of Different
           Extraction Conditions on Scavenging Activity of Helichrisym italicum
           (Roth) G. Don Extracts

    • Authors: Branislava Teofilović, Filip Balaž, Milica Karadžić Banjac, Nevena Grujić-Letić, Emilia Gligorić, Strahinja Kovačević, Sanja Podunavac-Kuzmanović, Srđan Stojanović
      First page: 436
      Abstract: Helichrysum italicum (Roth) G. Don is widely used as a liver stimulant and diuretic, as well as an antioxidant, antiallergenic, antimicrobial, antiviral, choleric, and antihypertensive agent. Therefore, the purpose of this study was to analyze the different extracts of H. italicum and to determine the relationship between total phenolic/flavonoid content and antioxidant activity. Plant material was pulverized to be 0.3 and 2 mm, and the extraction was obtained with 5 mL of different ethanol concentrations (30, 40, 50, 60, 96%, v/v) and water during different periods (10, 30, 60 min and 24 h) and with concentrated methanol (95%, v/v), dichloromethane, acetone, chloroform, ethyl acetate, and hexane during 10 and 30 min due to solvents volatility. Extracts were evaporated on the rotary evaporator. Total phenolic and flavonoid content were determined via spectrophotometric measurement, and antioxidant capacity was investigated by the inhibitory activity of DPPH radicals. The group of 92 extracts described through their TPC, flavonoids, yield, and IC50 values were subjected to PCA and HCA analysis. PCA and HCA were performed using Statistica v 10.0 software. The number of phenolic compounds ranged from 2.58 ± 0.1 to 43.60 ± 0.3 mg GAE/g of dry extract, and total flavonoids content ranged from 0.25 ± 0.01 to 23.96 ± 0.19 mg QE/g of dry extract. All extracts showed good antioxidant activity with an IC50 value in the range from 4.92 ± 0.2 to 231.12 ± 1.9 μg/mL. PCA and HCA analysis were performed on the whole data set comprising 92 extracts for both particle sizes (s0.3 and s2) as well as heat map analysis. It was found that the increased time of extraction, concentration of ethanol, and degree of fragmentation enhances the quality of the extracts in terms of phenolic component content and antioxidant effects. Applied chemometric analysis contributed to the extraction conditions grouping, overview, and selection in order to distinguish the extracts with the promising TPC, flavonoids, yield, and IC50 values.
      Citation: Separations
      PubDate: 2023-08-02
      DOI: 10.3390/separations10080436
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 437: Optimization of the Preparation of
           Hydrophilic Poly(DHPMA-co-MBA) Monolithic Capillary Columns: A New Support
           for Affinity Chromatography

    • Authors: Julie Gil, Gaëtan Passalacqua, Adrien Deloche, François-Xavier Vidal, Vincent Dugas, Claire Demesmay
      First page: 437
      Abstract: In miniaturized affinity chromatography, the development of hydrophilic organic monoliths with reduced non-specific interactions and high-protein grafting capacity remains a hot topic. In this work, we propose the one-step synthesis of a diol organic monolith to replace the gold-standard epoxy-based organic monoliths (which require post-modification, namely hydrolysis, prior to use). The synthesis of this new monolith builds upon the use of N-N’-Methylenebis(acrylamide) (MBA), as a hydrophilic crosslinker, and 2,3-dihydroxypropyl methacrylate (DHPMA), a diol monomer that eliminates the time-consuming epoxy ring opening step and its associated side reactions. The optimization of one-step synthesis parameters led to a monolith with a satisfactory permeability ((4.8 ± 0.5) × 10−14 m2), high efficiency (117,600 plates/m at optimum flow velocity (uopt = 0.09 cm s−1)) and reduced non-specific interactions. It is exemplified by its separation ability in the HILIC mode (separation of nucleosides), and by the retention data set of 41 test solutes, which were used to evaluate the non-specific interactions. This new poly(DHPMA-co-MBA) monolith has not only hydrophilic surface properties, but also improved protein grafting capacity compared to the glycidyl-based monolith (13 ± 0.7 pmol cm−1). The potential of this monolith is illustrated in affinity chromatography, where the concanavalin ligands are ranked according to their Kd values.
      Citation: Separations
      PubDate: 2023-08-02
      DOI: 10.3390/separations10080437
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 438: Removal of Pb(II) from Aqueous Solution
           and Adsorption Kinetics of Corn Stalk Biochar

    • Authors: Wenling Yang, Chaoyang Lu, Bo Liang, Chaohui Yin, Gao Lei, Baitao Wang, Xiaokai Zhou, Jing Zhen, Shujing Quan, Yanyan Jing
      First page: 438
      Abstract: In this work, the Pb adsorption and removal ability of biochar from simulated Pb(II)-contaminated wastewater, adsorption isotherms, kinetics, and thermodynamics were studied. Adsorption characteristics of biochar on Pb(II) were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS). The influence of the pH of the solution, the contact time, and the biochar dose on the removal of Pb(II) were investigated by single-factor design and response surface analysis. With the increase in biochar dose from 2 g/L to 4 g/L in wastewater, the Pb(II) amount adsorbed on biochar reduced from 21.3 mg/g to 17.5 mg/g. A weakly acidic environment was more conducive to the ligand exchange between Pb(II) ions and biochar. Pb(II) adsorption kinetics of biochar showed that the Pseudo-first-order model was more suitable than other employed models to describe the adsorption process. During the isothermal adsorption process, Langmuir and Freundlich’s isotherms fitted the adsorption data very well (R2 > 96%). The Pb (II) adsorption onto biochar was spontaneous in the specified temperature range (298–318 K) and the process was exothermic. Simultaneously, the optimal conditions were a pH of 5, a contact time of 255 min, and a biochar dose of 3 g/L, under which the maximum predicted Pb(II) removal efficiency was 91.52%.
      Citation: Separations
      PubDate: 2023-08-02
      DOI: 10.3390/separations10080438
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 439: Chromatographic Separations

    • Authors: Victoria Samanidou
      First page: 439
      Abstract: The topic of chromatographic separations is a recent addition to the Separations journal [...]
      Citation: Separations
      PubDate: 2023-08-02
      DOI: 10.3390/separations10080439
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 440: Enhancement of Photocatalytic Rhodamine B
           Degradation over Magnesium–Manganese Baring Extracted Iron Oxalate
           from Converter Slag

    • Authors: Chitiphon Chuaicham, Jirawat Trakulmututa, Sulakshana Shenoy, Vellaichamy Balakumar, Phatchada Santawaja, Shinji Kudo, Karthikeyan Sekar, Keiko Sasaki
      First page: 440
      Abstract: In this work, iron oxalate from converter slag (FeOX-Slag) was produced by extraction of iron from converter slag using oxalic acid, followed by photo-reduction. The FeOX-Slag sample was subjected to various characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL), X-ray absorption near-edge structure spectroscopy (XANES), and X-ray photoelectron spectroscopy (XPS), in order to gain insights into its physicochemical properties. Also, to compare the photocatalytic activity of the FeOX-Slag, commercial iron oxide (Fe2O3) was used as a precursor to produce normal iron oxalate (FeOX-Fe2O3). The obtained FeOX-Slag was applied to the photocatalytic degradation of rhodamine B (RhB), a model organic contaminant in wastewater, compared with the FeOX-Fe2O3. Using the produced FeOX-Slag, we were able to degrade RhB more than 98% within 90 min at a reaction rate constant of about 3.6 times faster than FeOX-Fe2O3. Photoluminescence results confirmed the less recombination of the electron–hole pairs in FeOX-Slag, compared to FeOX-Fe2O3, which may be due to the defect structure of iron oxalate by guest metal impurities. The higher separation and transportation of photogenerated electron–hole pairs cause the enhancement of the degradation photocatalytic RhB degradation activity of the FeOX-Slag. In addition, The FeOX-Slag showed higher light absorption ability than FeOX-Fe2O3, resulting in the enhancement of the RhB degradation performance. Thus, the optical properties and the results from the activity tests led to the proposal that FeOX-Slag may be used in a photocatalytic degradation process for RhB under light irradiation.
      Citation: Separations
      PubDate: 2023-08-03
      DOI: 10.3390/separations10080440
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 441: Enhanced Adsorption of Chromate and
           Arsenate Ions from Contaminated Water with Emphasis on Polyethylenimine
           Modified Materials: A Review

    • Authors: Maria Xanthopoulou, Ioannis A. Katsoyiannis
      First page: 441
      Abstract: Heavy metals in water pose a great threat to human health, and water treatment remains a critical issue globally. Among various water treatment techniques, adsorption has been proven to be an excellent way to remove heavy metals from water due to its advantages, like low cost, availability, profitability, ease of operation, and efficiency. Heavy metals such as chromium and arsenic are present in water in the form of anions, while many common adsorbents, such as biochar and activated carbons, cellulose, chitosan, clays, and silica, tend to acquire a negative surface charge. The surface charge of the adsorbent plays a major role in its interaction with heavy metal ions. Polyethylenimine is a polymer with a high cationic charge density. Modification of these adsorbents with polyethylenimine results in higher selectivity for these anions. The adsorption capacity is related to the efficiency of the introduction of polyethylenimine, which depends on the surface properties of the adsorbent. This review focuses on the effect of modification with polyethylenimine on the adsorption capacity of common adsorbents for the removal of heavy metal ions, such as chromate and arsenate, from water.
      Citation: Separations
      PubDate: 2023-08-07
      DOI: 10.3390/separations10080441
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 442: Effects of Catha edulis (Khat) on the
           Pharmacokinetics of Metformin in Diabetic Rats Using UPLC/MS/MS Analysis
           and Its Impact on Hepatic CYP450 Enzymes

    • Authors: Ali S. Alqahtani, Mohammad Khalid Parvez, Abdulaziz M. Alqahtani, Omer I. Fantoukh, Rashed N. Herqash, Ehab M. Elzayat, Fahd A. Nasr, Essam Ezzeldin, Mousallam M. Almousallam, Mohammad Raish
      First page: 442
      Abstract: Catha edulis Forsk., commonly known as Khat, is a stimulant plant that is chewed in the Horn of Africa and the southern regions of the Arabian Peninsula. It is often used alongside conventional drugs, but there is a lack of research on its interactions with other drugs. In this study, our aim was to investigate the possibility of an herb–drug interaction between KT extract and metformin (MT) by exploring the effect of KT on the in vivo pharmacokinetics of MT in diabetic Wistar albino rats and monitoring blood glucose levels through time intervals, comparing when MT was given alone and co-administered with KT. Rats were given 500 mg/kg of KT extract and 300 mg/kg of MT daily for 7 days. The pharmacokinetic parameters of MT were analyzed using UPLC-MS/MS. The quantification was conducted using multiple reaction monitoring (MRM) in positive ion mode. The transitions used were (m/z) 130.006→59.939 for MT and 260.125→116.018 for propranolol as an internal standard (IS). An Acquity UPLC BEH HSS T3 C18 column was used with isocratic elution, and the mobile phase was formic acid (0.1%): acetonitrile (70:30 v/v) at a flow rate of 0.25 mL/min. In addition, the study delved into the in vitro impact of KT on the CYP3A4 enzyme, seeking to identify any potential disruptions in MT’s metabolism that could alter its pharmacokinetics. The effect of KT extract on CYP3A4 enzyme activity was investigated using fluorescence-based enzyme assays and a CYP3A4 Inhibitor Screening Kit. The results indicated that the combined treatment showed increased systemic exposure to MT, with Cmax and AUC levels increasing by 33.42% and 45.23%, respectively. Additionally, the combination treatment led to significantly lower fasting blood glucose (FBG) levels compared to the groups treated with MT alone. It was found that at a concentration of 500 µg/mL, the CYP3A4 enzyme activity was maximally suppressed by approximately 57%, while at 250 µg/mL, it was inhibited by almost 50%. In comparison, the standard Ketoconazole only inhibited CYP3A4 activity by approximately 58%. Therefore, the in vitro results suggest that KT extract has the potential to affect CYP3A4 activity at high doses. In conclusion, the combination treatment resulted in a significant increase in MT’s blood sugar-lowering effects. Therefore, it is important to be aware of this potential interaction and to monitor blood sugar levels closely when using KT alongside MT.
      Citation: Separations
      PubDate: 2023-08-08
      DOI: 10.3390/separations10080442
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 443: In-Line Measurement of Extraction Process
           by Slug Flow and Determination of Mass Transfer Parameters

    • Authors: Takamichi Okamoto, Akinori Muto
      First page: 443
      Abstract: The primary objective of this study was to pragmatically implement an extraction process using slug flow, wherein two immiscible phases, aqueous and oil, are alternatively channeled through a conduit to encourage mass exchange across the interface. To facilitate this, we introduced and empirically validated an in-line technique to precisely quantify the length of the slug and the potential extraction concentration of the two aforementioned phases. The length of the slug and its concentration were ascertained through conductivity, utilizing platinum wire as the electrode. This method consistently produced results with a maximum error margin of ±5%. Using this apparatus, we determined key mass transfer parameters, including the overall mass transfer coefficient. Notably, as the linear velocity amplified, so did the extraction rate. These findings present a significant opportunity for enhancing the efficiency of the extraction process and enabling its optimization.
      Citation: Separations
      PubDate: 2023-08-08
      DOI: 10.3390/separations10080443
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 444: The Development and Validation of a
           Targeted LC-HRAM-MS/MS Methodology to Separate and Quantify p-Synephrine
           and m-Synephrine in Dietary Supplements and Herbal Preparations

    • Authors: Celine Vanhee, Sophia Barhdadi, Angélique Kamugisha, Tanika Van Mulders, Kevin Vanbrusselen, Marie Willocx, Eric Deconinck
      First page: 444
      Abstract: Dietary supplements containing Citrus aurantium or p-synephrine remain very popular in Europe and the United States of America (USA). They are primarily sold as weight loss enhancers, although their efficacy and the safety are still under scrutiny. To this end, several countries have set maximum threshold levels of p-synephrine that are permitted in dietary supplements. Moreover, there have also been reports of possible chemical adulteration of these supplements with the synthetic positional isomer, m-synephrine, known to be used as a medicinal product. Therefore, it is pivotal for regulatory agencies to be able to discriminate between the two positional isomers and also quantify the amount of each when encountered in dietary supplements. Here, we present the development and the validation of a simple and fast “dilute and shoot” procedure, employing liquid chromatographic (LC) separation in combination with high-resolution accurate mass (HRAM) tandem mass spectroscopy (LC-HRAM-MS/MS) to separate these two isomers and subsequently quantify them. The quantification methodology has been validated using the “total error approach”, applying accuracy profiles, and is consequently compliant with ISO17025. Moreover, ten real-life samples, either purchased online or encountered by Belgian regulatory agencies, were analyzed using the described procedure. Startlingly, only one sample out of ten was compliant with Belgian legislation in terms of labeling, the presence of a batch number, expiration date and dosage (with a tolerated error of ±20%). Moreover, three samples also contained banned substances such as yohimbine and sibutramine.
      Citation: Separations
      PubDate: 2023-08-09
      DOI: 10.3390/separations10080444
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 445: High-Degree Oxidative Desulfurization of
           a Commercial Marine Fuel Using Deep Eutectic Solvents and Their Recycling

    • Authors: Olga Thoda, Efstratios Svinterikos, Konstantinos Miltiadis Sakkas, Anastasia Maria Moschovi, Iakovos Yakoumis
      First page: 445
      Abstract: Escalating environmental concerns have dictated the need to develop innovative methods for efficiently desulfurizing marine fuels (heavy fuel oils). In this work, the oxidative desulfurization method using deep eutectic solvents (DESs) was applied to reduce the sulfur content in a commercially available heavy fuel oil (HFO) below 0.5 wt.%, as current regulations demand. Initially, the S-compounds in the fuel were oxidized using an oxidative mixture of H2O2 with carboxylic acid (either acetic or formic acid). Subsequently, the oxidized S-compounds were extracted from the fuel using a series of environmentally friendly deep eutectic solvents (DESs), the best of which was proven to be a mixture of choline chloride with ethylene glycol at a 1/2 molar ratio. The process was optimized by investigating the effect of several process parameters on the desulfurization efficiency, namely, the H2O2/S molar ratio, the H2O2/acid molar ratio, the acid type, the oxidation temperature and oxidation time, the solvent/fuel mass ratio, the extraction time, and the extraction temperature. A desulfurization efficiency of 75.7% was achieved under the optimized conditions, reducing the S content in the fuel to 0.33 wt.%. Furthermore, different methods to recycle the DESs were investigated, and consecutive desulfurization and solvent regeneration cycles were performed. The most efficient recycling method was determined to be the anti-solvent addition of excess water, which resulted in 89.5% DES purification by causing precipitation of the dissolved solids. After three cycles of desulfurization and regeneration using different recycling routes, it was found that the regeneration degree declines gradually; however, it is more than 79.3% in all cases.
      Citation: Separations
      PubDate: 2023-08-09
      DOI: 10.3390/separations10080445
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 446: Representative Elementary Volume
           Estimation and Neural Network-Based Prediction of Change Rates of Dense
           Non-Aqueous Phase Liquid Saturation and Dense Non-Aqueous Phase
           Liquid–Water Interfacial Area in Porous Media

    • Authors: Zhou Cheng, Guoping Lu, Ming Wu, Qusheng Li
      First page: 446
      Abstract: Investigation of the change rate for contaminant parameters is important to characterize dense non-aqueous phase liquid (DNAPL) transport and distribution in groundwater systems. In this study, four experiments of perchloroethylene (PCE) migration are conducted in two-dimensional (2D) sandboxes to characterize change rates of PCE saturation (So) and PCE–water interfacial area (AOW) under different conditions of salinity, surface active agent, and heterogeneity. Associated representative elementary volume (REV) of the change rate of So (So rate) and change rate of AOW (AOW rate) is derived over the long-term transport process through light transmission techniques. REV of So rate (SR-REV) and REV of AOW rate (AR-REV) are estimated based on the relative gradient error (εgi). Regression analysis is applied to investigate the regularity, and a model based on a back-propagation (BP) neural network is built to simulate and predict the frequencies of SR-REV and AR-REV. Experimental results indicated the salinity, surface active agent, and heterogeneity are important factors that affect the So rate, AOW rate, SR-REV, and AR-REV of the PCE plume in porous media. The first moment of the PCE plume along the vertical direction is decreased under conditions of high salinity, surface active agent, and heterogeneity, while these factors have different effects on the second moment of the PCE plume. Compared with the salinity and surface active agent, heterogeneity has the greatest effect on the GTP, the distributions of the So rate and AOW rate along the depth, and dM, dI. For SR-REV, the standard deviation is increased by the salinity, surface active agent, and heterogeneity. Simultaneously, the salinity and heterogeneity lead to lower values of the mean value of SR-REV, while the surface active agent increases the mean value of SR-REV. However, the mean and standard deviation of AR-REV have no apparent difference under different experimental conditions. These findings reveal the complexity of PCE transport and scale effect in the groundwater system, which have important significance in improving our understanding of DNAPL transport regularity and promoting associated prediction.
      Citation: Separations
      PubDate: 2023-08-10
      DOI: 10.3390/separations10080446
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 447: Comparison of Miniaturized
           Chromatographic Columns and 96-Well Plates for Automated Antibody
           Purification under Economic and Sustainable Aspects

    • Authors: Anna Bach, Heidi Fleischer, Kerstin Thurow
      First page: 447
      Abstract: Therapeutic antibodies are an area of major interest in treating infectious diseases, autoimmune diseases, and cancer. Efficient purification strategies are required to discover and produce antibodies, representing a significant cost driver. Miniaturization and automation of the chromatographic purification process may contribute to cost reduction. In this article, miniaturized chromatographic columns and 96-well filter plates are used to purify an IgG antibody from cell cultures and are compared in terms of quality, cost, and sustainability. The validation results of the two miniaturized chromatographic antibody purification methods indicate high efficacy and are comparable except for minor differences in yield. The lowest cost per sample can be obtained with the miniaturized chromatographic columns, as annual throughput can be maximized with the miniaturized plates. By evaluating sustainability, significant reductions in laboratory waste produced during antibody purification can be shown, along with an increase in employee safety by using the automation system. Overall, the comparison of results shows that, in the development of new purification strategies, the type of implementation has a decisive influence on the outcomes in terms of recovery, cost-effectiveness, and sustainability.
      Citation: Separations
      PubDate: 2023-08-11
      DOI: 10.3390/separations10080447
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 448: Expression, Purification and
           Characterization of a Novel Rusticyanin from the Psychrotolerant
           Acidithiobacillus ferrivorans

    • Authors: Yuandong Liu, Lixiang Chen, Xiangdong Shangguan, Jingying Ouyang, Jiayu He, Kan Wang, Yan Tong, Runlan Yu, Weimin Zeng, Xueling Wu, Li Shen, Guanzhou Qiu
      First page: 448
      Abstract: Rusticyanin plays a crucial role in ferrous oxidation of sulfide minerals during bioleaching for industrial metal extraction. Diverse isoforms of rusticyanin have been found, but until now, except for type-A rusticyanin, other isoforms or sources of rusticyanin have been scarcely investigated. Here, a rusticyanin (gene locus 0470) from the psychrophilic Acidithiobacillus ferrivorans was gene-cloned, expressed, purified, and assembled in vitro. All forms of the protein exhibit extreme acid stability, even at pH 0.3. The stability of the protein is obviously enhanced after binding of the copper cofactor; the oxidation state is more stable than the reduced state. The protein has characteristic UV-vis peaks and EPR signals similar to type-A or type-B rusticyanin but is different with a small position shift and an obvious intensity change. The vibrational spectrum of the apoprotein was more different than these between the oxidation and reduced states of the protein. The ferrous oxidation kinetic rate constant of the protein is obviously faster than that of both the type-A and type-B rusticyanins previously reported. Further bioinformatics analysis reveal their changes in sequence and molecule: the mutations related to the peculiar shield belt mostly account for the variation in the properties of the protein, and the classification of the protein as a new isoform, type-C rusticyanin, is proposed.
      Citation: Separations
      PubDate: 2023-08-13
      DOI: 10.3390/separations10080448
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 449: Analytical and Preparative Separation of
           Softwood Lignans by Supercritical Fluid Chromatography

    • Authors: Nikolay V. Ul’yanovskii, Aleksandra A. Onuchina, Denis V. Ovchinnikov, Anna V. Faleva, Natalia S. Gorbova, Dmitry S. Kosyakov
      First page: 449
      Abstract: Lignans are widespread polyphenolic secondary plant metabolites possessing high biological activity. One of the most promising industrial-scale sources of such compounds is coniferous knotwood, containing a large number of polyphenolic compounds. Their use in pharmaceutical and other industries is limited by the difficulty in obtaining high-purity preparations from plant material and the requirement of advanced separation techniques. In this study, supercritical fluid chromatography on polar stationary phases was proposed for the efficient separation and identification of spruce, pine, fir, and larch knotwood extractives. Among the six tested sorbents, the best results were shown by silica with grafted diol and 2-ethylpyridine groups under conditions of gradient elution with a carbon dioxide–methanol mobile phase, which ensured the efficient retention and separation of analytes due to donor–acceptor interactions. Scaling up the method on a DIOL stationary phase provided a semi-preparative separation of extractives within 30 min to obtain 14 individual compounds with a purity of 90–99% and yields from 0.3 to 51% of the dry extract. These included eight lignans (nortrachelogenin, matairesinol, oxomatairesinol, α-conidendrin, 5-hydroxymatairesinol and its isomer, lariciresinol, and secoisolariciresinol), two oligolignans, three stilbenes (pinosylvin and its methyl ester, pterostilbene), and flavonoid taxifolin. The developed approach is distinguished with low operational costs, low consumption of organic solvents, environmental safety, and it is fully consistent with the principles of green chemistry.
      Citation: Separations
      PubDate: 2023-08-13
      DOI: 10.3390/separations10080449
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 450: A Fast LC-MS/MS Methodology for
           Estimating Savolitinib in Human Liver Microsomes: Assessment of Metabolic
           Stability Using In Vitro Metabolic Incubation and In Silico Software

    • Authors: Mohamed W. Attwa, Haitham AlRabiah, Ali S. Abdelhameed, Adnan A. Kadi
      First page: 450
      Abstract: Savolitinib (Orpathys®), was developed by (HUTCHMED (Shanghai, China) and, AstraZeneca (Gaithersburg, Maryland, USA), is an inhibitor of the c-Met receptor tyrosine kinase that is orally bioavailable. It was designed for the treatment of pillary and clear-cell renal-cell carcinoma (RCC), colorectal cancer, gastric cancer, and metastatic non-small-cell lung cancer (NSCLC). The current work aimed to develop a rapid, specific, green, and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) methodology for estimating savolitinib (SVB) in human liver microsomes (HLMs) with application to an in vitro metabolic stability assessment of SVB in HLMs. The validation steps of the current LC-MS/MS methodology in the HLMs were carried out following US FDA bioanalytical method validation guidelines including sensitivity, selectivity, linearity, accuracy, stability, precision, extraction recovery, and matrix effect. SVB and olmutinib (OLM) were chromatographically separated on an Eclipse Plus C8 column using an isocratic mobile phase. SVB parent ions were generated using the positive mode of an electrospray ionization (ESI) source. SVB daughter ions were detected and quantified using the multiple reaction monitoring (MRM) mode of a triple quadrupole mass analyser. The constructed SVB calibration curve showed linearity over the range from 1 to 3000 ng/mL. The interday and intraday accuracy and precision of the developed LC-MS/MS analytical methodology were −6.67%–4.11% and −0.51%–8.75%, respectively. A lower limit of quantification (LLOQ) of 0.87 ng/mL confirmed the sensitivity of the established method. Furthermore, the eco-scale methodology using the in silico AGREE software was used for the greenness assessment of the current LC-MS/MS method, and the outcomes showed that the established method was very eco-friendly. The intrinsic clearance (Clint) and in vitro half-life (t1/2) of SVB were 33.05 mL/min/kg and 24.54 min, respectively. SVB exhibited a moderate extraction ratio. The current study is the first to establish and validate LC-MS/MS for estimating SVB and assessing the metabolic stability of SVB.
      Citation: Separations
      PubDate: 2023-08-14
      DOI: 10.3390/separations10080450
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 451: Study on Treatment Performance of
           Desulfurization Wastewater by Zero-Valent Iron Fenton-like Process

    • Authors: Ziguo Liu, Wei Zhou, Xianli Liu, Xuefen Yang, Wei Yang, Han Zheng
      First page: 451
      Abstract: In this study, the zero-valent iron Fenton reagent (ZVI Fenton-like) system was combined with the chemical precipitation method for the deep treatment of desulfurization wastewater from coal-fired power plants, and the chemical oxygen demand (COD) was used as the evaluation criterion for organic matter in the desulfurization wastewater. The effects of reaction time, H2O2 dosage, zero-valent iron dosage, pH, and reaction temperature were also investigated. The results showed that the COD concentration of the effluent was the lowest when the running time of the ZVI Fenton-like reagent system was 1 h, the dosage of H2O2 was 33.3 mg·L−1, the dosage of iron was 0.075 g·L−1, the pH was 4.5~6.5, the reaction temperature was 35 °C, the COD concentration of the wastewater was the lowest and its operating conditions were the best, and the internal reaction mechanism was finally deduced. In summary, the zero-valent iron Fenton reagent system provides a new idea for the treatment of desulfurization wastewater from coal-fired power plants.
      Citation: Separations
      PubDate: 2023-08-14
      DOI: 10.3390/separations10080451
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 452: Solid–Liquid Extraction of
           Bioactive Molecules from White Grape Skin: Optimization and Near-Infrared

    • Authors: Tea Sokač Cvetnić, Korina Krog, Maja Benković, Tamara Jurina, Davor Valinger, Jasenka Gajdoš Kljusurić, Ivana Radojčić Redovniković, Ana Jurinjak Tušek
      First page: 452
      Abstract: In this work, the solid–liquid extraction of bioactive molecules from grape skin was performed using water as the extraction solvent. The effects of extraction time (t = 60, 75, and 90 min), extraction temperature (T = 40, 60, and 80 °C), solid–liquid phase ratio (S/L = 10, 20, and 30 g/L), and mixing speed (rpm = 250, 500, and 750 1/min) on the total dissolved solids, extraction yield, concentration of total polyphenols, and antioxidant activity were determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. According to response surface modeling, the optimal extraction conditions were t = 75 min, T = 80 °C, S/L = 30 g/L, and rpm = 750 1/min, and under optimal process conditions, 8.38 mgGAE/gd.m. was obtained. Furthermore, the potential of near-infrared (NIR) spectroscopy coupled with artificial neural network (ANN) modeling for prediction of the physical and chemical properties of prepared extracts was also analyzed. The use of ANN modeling demonstrated highly favorable correlations between the NIR spectra and all the variables tested, particularly the total dissolved solids (TDS) and antioxidant activity measured using the FRAP method. As a result, ANN modeling proved to be a valuable tool for predicting the concentration of total polyphenols, the antioxidant activity, and the extraction yield of a plant extract based on its NIR spectra.
      Citation: Separations
      PubDate: 2023-08-14
      DOI: 10.3390/separations10080452
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 453: MALDI-TOF MS: A Promising Analytical
           Approach to Cancer Diagnostics and Monitoring

    • Authors: Patrícia Sousa, Laurentina Silva, Catarina Luís, José S. Câmara, Rosa Perestrelo
      First page: 453
      Abstract: Cancer remains the second most common cause of death after cardiovascular diseases, accounting for nearly 10 million deaths in 2020. Although the incidence of cancer increases considerably with age, the cancer burden can also be reduced and have a high chance of cure through early detection, appropriate treatment, and care of patients. The development of high-throughput analytical approaches, like matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), contributes to identifying a pool of proteins/peptides as putative biomarkers for the early detection, diagnosis, and tumor progression. The purpose of the current review is to present an updated outline of recent proteome/peptidome research to establish putative cancer biomarkers using MALDI-TOF MS and highlight the applicability of statistical analysis in the oncology field. The pros and cons of MALDI-TOF MS application on cancer diagnostics and monitoring will be discussed, as well as compared with tandem mass spectrometry (MS/MS)-based proteomics (e.g., liquid chromatography–tandem mass spectrometry). In addition, pre-analytical (e.g., sample quality control) and analytical (e.g., sample pre-treatment, instrumental analytical conditions) properties that influence the robustness of MALDI-TOF MS data will be also discussed.
      Citation: Separations
      PubDate: 2023-08-14
      DOI: 10.3390/separations10080453
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 454: Molecularly Imprinted Polymer-Based
           Nanoporous Carbon Nanocomposite for Effective Adsorption of Hg(II) Ions
           from Aqueous Suspensions

    • Authors: Lawal Abubakar, Nor Azah Yusof, Abdul Halim Abdullah, Faruq Mohammad, Mohd Hanif Wahid, Suhainie Ismail, Zulaiha Abdul Rahim, Hamad A. Al-Lohedan, Ahmed A. Soleiman
      First page: 454
      Abstract: Due to the release of hazardous heavy metals from various industries, water pollution has become one of the biggest challenges for environmental scientists today. Mercury Hg(II) is regarded as one of the most toxic heavy metals due to its ability to cause cancer and other health issues. In this study, a tailor-made modern eco-friendly molecularly imprinted polymer (MIP)/nanoporous carbon (NC) nanocomposite was synthesized and examined for the uptake of Hg(II) using an aqueous solution. The fabrication of the MIP/NC nanocomposite occurred via bulk polymerization involving the complexation of the template, followed by polymerization and, finally, template removal. Thus, the formed nanocomposite underwent characterizations that included morphological, thermal degradation, functional, and surface area analyses. The MIP/NC nanocomposite, with a high specific surface area of 884.9 m2/g, was evaluated for its efficacy towards the adsorptive elimination of Hg(II) against the pH solution changes, the dosage of adsorbent, initial concentration, and interaction time. The analysis showed that a maximum Hg(II) adsorption effectiveness of 116 mg/g was attained at pH 4, while the Freundlich model fitted the equilibrium sorption result and was aligned with pseudo-second-order kinetics. Likewise, thermodynamic parameters like enthalpy, entropy, and Gibbs free energy indicated that the adsorption was consistent with spontaneous, favorable, and endothermic reactions. Furthermore, the adsorption efficiency of MIP/NC was also evaluated against a real sample of condensate from the oil and gas industry, showing an 87.4% recovery of Hg(II). Finally, the synthesized MIP/NC showed promise as a selective adsorbent of Hg(II) in polluted environments, suggesting that a variety of combined absorbents of different precursors is recommended to evaluate heavy metal and pharmaceutical removals.
      Citation: Separations
      PubDate: 2023-08-17
      DOI: 10.3390/separations10080454
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 455: Evaluation of BPA and Bis-GMA Release
           from Recent Dental Composite Materials by LC-MS/MS

    • Authors: Lígia Lopes-Rocha, Virgínia M. F. Gonçalves, Sara C. Cunha, José O. Fernandes, Teresa Pinho, Maria Elizabeth Tiritan
      First page: 455
      Abstract: Bisphenol-A (BPA) is a xenoestrogen widely used as a synthetic precursor of resin monomers. There is arise need to acquire BPA-free resin-matrix composites to prevent the health effects of BPA. Six composites with distinctive manufacturer specifications were considered to evaluate the degree of release of BPA and bisphenol A-Diglycidyl Methacrylate (Bis-GMA) in a dental composite. The light-cured resin-matrix specimens (n = 5 for each composite type) were incubated at 37 °C in 1 mL of a 75% ethanol–water solution in a sealed amber glass vial for 7 days. The 75% ethanol–water solution was replaced daily and immediately frozen (−20 °C) until liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. BPA was not detected in any studied resin-based materials. However, Bis-GMA was detected in almost all the studied samples during the experiment, except AF and BF. The highest Bis-GMA concentration was released from ED at 67.43 ng/mL, followed by BE, FS, and NC with 40.75 ng/mL, 8.30 ng/mL, and 0.94 ng/mL, respectively. There is a clear need for more precise and standardized analytical methods to assess the short- and long-term release of resin-based materials. Furthermore, manufacturers should be obliged to provide complete details of the chemical composition of dental products and to promote the development of materials without estrogenic potential.
      Citation: Separations
      PubDate: 2023-08-18
      DOI: 10.3390/separations10080455
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 456: Determining the Hydrophobicity Index of
           Protected Amino Acids and Common Protecting Groups

    • Authors: Varshitha Gavva, Othman Al Musaimi, Colin Bent, Daryl R. Williams
      First page: 456
      Abstract: Peptides are in great demand in the pharmaceutical arena and a majority of these peptides contain 20 or more amino acids. They are infrequently synthesised using the fragment condensation approach. A key limitation in adopting this approach more commonly is that protected peptide fragments with high purity are often required prior to the final condensation steps. It is hypothesized that understanding the hydrophobic nature of the protected amino acids will assist with designing optimal fragment purification processes when needed. Whilst a myriad of hydrophobicity indices are reported in the literature for unprotected amino acids, the literature lacks any data regarding the protected amino acids which form the key precursor for the fragment condensation task. In this current study, hydrophobicity indices for protected amino acids with common α-amino and sidechain protecting groups were experimentally determined. Different positions for each amino acid within the peptide chain were considered, namely at the C-terminal and N-terminal as well as internal positions. These data give deep insights on the hydrophobicity of each amino acid with respect to its position in the peptide chain. The data acquired in this research facilitated the prediction of the retention time of protected peptide fragments with an uncertainty of less than ±1.5%.
      Citation: Separations
      PubDate: 2023-08-20
      DOI: 10.3390/separations10080456
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 457: UHPLC-ToF-MS as a High-Resolution Mass
           Spectrometry Tool for Veterinary Drug Quantification in Milk

    • Authors: Marta Leite, Ana Rita Marques, Ana Sofia Vila Pouca, Silvia Cruz Barros, Jorge Barbosa, Fernando Ramos, Isabel Maria Afonso, Andreia Freitas
      First page: 457
      Abstract: Milk is one of the most widely consumed foods in the world, despite the increasing consumption of plant-based alternatives. Although rich in nutrients and believed by consumers to be free of undesirable contaminants, milk, whether of animal or plant origin, is not always free from residues of chemical substances, including veterinary medicines. For instance, in intensive livestock production, antibiotics are often used to treat animals or, illicitly, to improve their growth performance, which can lead to their presence in the final food. Additionally, the continuous use of veterinary drugs in intensive animal production can lead to their occurrence in agricultural soils and therefore are absorbed by plants as another source of entering the food chain. An effective and accurate multi-detection quantitative screening method to analyze 89 antibiotics in milk was optimized by ultra-high-performance liquid chromatography coupled with a time-of-flight detector (UHPLC-ToF-MS) and further validated in accordance with the Commission Implementing Regulation (CIR) 808/2021 and the International Council for Harmonization (ICH) guidelines on the validation of analytical procedures. Apart from the specific parameters required by CIR 808/2021, the aim was to access the lower limits of the method, limits of detection (LoD) and quantification (LoQ), regardless of the maximum residue limits (MRLs) defined in the legislation. The method was then applied in the analysis of 32 supermarket samples, resulting in four positive findings, including one plant-based sample. The antibiotics found were from the macrolides and sulphonamides families. Nevertheless, the concentrations detected were below the established maximum residue level (MRL).
      Citation: Separations
      PubDate: 2023-08-21
      DOI: 10.3390/separations10080457
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 458: Impact of Cumin (Cuminum cyminum)
           Incorporation on the Generation of Heterocyclic Aromatic Amines in

    • Authors: Elif Ekiz, Adem Savaş, Eyad Aoudeh, Zeynep Elbir, Emel Oz, Charalampos Proestos, Naushad Ahmad, Fatih Oz
      First page: 458
      Abstract: In the current study, the impacts of using cumin (0.5% and 1%, w/w) in beef meatballs on heterocyclic aromatic amines (HAAs) formation and some quality characteristics when cooked at 150 and 250 °C were investigated. It was found that using of cumin at different ratios in beef meatballs showed a significant (p < 0.01) effect on pH, thiobarbituric acid reactive (TBARS) value, and total HAA. The cooking process significantly (p < 0.01) affected the meatballs’ water content, pH, and TBARS values, while the cooking loss and total HAA content of meatballs were significantly (p < 0.01) affected by cooking temperature. It was found that the cumin usage rate in meatballs increased the pH value, while it was found to decrease the TBARS value. As expected, the cooking process was associated with a reduction in water, while it was found to result in an increase in the pH and TBARS values. On the other hand, both cooking temperature and cumin addition to meatballs led to an increase in their total HAA content. Diverse samples exhibited detectable levels of IQx, MeIQx, MeIQ, and PhIP compounds. The presence of MeIQx compound was found in all samples, except for the control group cooked at 150 °C. Additionally, the use of 0.5% and 1% cumin in meatballs cooked at temperature of 250 °C had an inhibitory effect on MeIQx compound. Our results revealed that the incorporation of cumin in the meatballs resulted in an increase in the total HAA content, likely due to its prooxidant effect. However, it was found that the use of cumin at certain rates could reduce the formation of MeIQx compound with an antioxidant effect. However, in this study found that even if 100 g of meatballs with the highest concentration of total HAA were consumed, the maximum HAA exposure limit value (0–15 µg/day) was not exceeded.
      Citation: Separations
      PubDate: 2023-08-21
      DOI: 10.3390/separations10080458
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 459: Optimization of QuEChERS Method for
           Antibiotic Residue Analysis in Animal Foods via Response Surface

    • Authors: Xiaoqiong Wu, Yun Lin, Xiang Zhang, Nan Ouyang, Ying Zhou
      First page: 459
      Abstract: The present study employed a modified QuEChERS method to systematically analyze the presence of fifteen quinolone and seven tetracycline antibiotic residues in local animal food. Additionally, a multi-level four-factor Box–Behnken design (BBD) within the framework of response surface methodology (RSM) was utilized to evaluate the factors impacting the detection efficiency of the sample pretreatment procedure. Optimization was performed via Design Expert® 10.0.3, and the factors, including the volume of the acetonitrile, the addition of formic acid, the duration of the extraction, and the addition of EDTA, were combined with experimental design until an optimal solution was reached. Finally, the sample was tested via ultra-high performance liquid chromatography-quadrupole-linear ion trap mass spectrometry (UPLC/MS/MS) in both multiple reaction monitoring (MRM) and enhanced product ion (EPI) scan modes on a QTRAP® 5500 instrument (AB SCIEX instruments, Framingham, MA, USA). The overall average recoveries from actual samples fortified with 22 antibiotics at three levels ranged from 73.8% to 98.5% based on the use of matrix-fortified calibration, with variations ranging from 5.80 to 12.4% (n = 6). The limits of detection and quantification were 0.3 μg kg−1 and 1.0 μg kg−1, respectively. Lastly, the modified method was applied to practical sample analysis in the daily risk monitoring and assessment of food safety with satisfactory stability and robustness.
      Citation: Separations
      PubDate: 2023-08-21
      DOI: 10.3390/separations10080459
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 460: A Green and Cost-Effective
           Chromatographic Method for the Measurement of the Activity of Human Serum

    • Authors: Chiara de Giacomi, Luca Regazzoni
      First page: 460
      Abstract: Carnosinase (i.e., CN1; E.C. is an enzyme found in the sera of higher primates. CN1 preferentially catalyzes the hydrolysis of natural, orally adsorbed histidine dipeptides like carnosine (i.e., β-alanyl-L-histidine). This is the reason why carnosine has a limited use as a human food supplement or pharmacological agent, despite the promising results obtained in experiments on animal models of human diseases. Herein, an assay is reported for the measurement of serum CN1 activity. The method is intended for the screening of CN1 inhibitors able to enhance carnosine bioavailability in humans. The method was developed to monitor serum hydrolytic activity via the quantitation of one of the products of carnosine hydrolysis (i.e., histidine). Separation was achieved without using organic solvents by means of ion chromatography (IC), whereas detection was provided by UV spectroscopy. The assay herein reported is a green and cost-effective alternative to a recently published method based on hydrophilic interaction liquid chromatography (HILIC) and mass spectrometry (MS). The results show that such a method produces reliable measurements of serum hydrolytic activity and can be used for the screening of CN1 inhibitors.
      Citation: Separations
      PubDate: 2023-08-21
      DOI: 10.3390/separations10080460
      Issue No: Vol. 10, No. 8 (2023)
  • Separations, Vol. 10, Pages 417: Enantioselective Separation of Synthetic
           Cathinones by Capillary Electrophoresis with Ionic Liquid and Cyclodextrin
           Buffer Co-Additives

    • Authors: Roberts, Colyer
      First page: 417
      Abstract: The enantioselective separation of synthetic cathinones via capillary electrophoresis with ultraviolet detection (CE-UV) was successfully achieved using an acidic formate buffer with the ionic liquid tetrabutylammonium chloride (TBAC) and beta-cyclodextrin (β-CD) as co-additives. Synthetic cathinones (also known as “bath salts”) belong to a class of unregulated drugs labeled new psychoactive substances (NPS). These drugs are readily available and can cause paranoia, confusion, violence, and suicidal thoughts. The stereochemistry of synthetic cathinones, as with other drugs, can influence their potency, toxicity, metabolism, and interaction with other molecules. Thus, it is important to be able to effectively separate different types of synthetic cathinone as well as to resolve enantiomers of each. A study of buffer additives, pH, and counter ions was conducted to identify a system yielding complete enantioselective separation of synthetic cathinones by capillary electrophoresis. Buffer additives TBAC and β-CD, when used separately, did not afford the desired separation; however, when employed as co-additives, enantiomers of each of six different bath salt standards (pentylone, 4-MEC, methylone, MDPBP, MDPV, and naphyrone) were resolved. Achieving this separation of a complex mixture of closely related illicit drugs by CE using an ionic liquid and cyclodextrin together, as buffer co-additives, may provide a new starting point from which to approach the enantiomeric analysis of other drug samples as syntheses of NPS continue to rapidly evolve to evade regulation and law enforcement.
      Citation: Separations
      PubDate: 2023-07-24
      DOI: 10.3390/separations10070417
      Issue No: Vol. 10, No. 7 (2023)
  • Separations, Vol. 10, Pages 418: Clarification of the Cardoon (Cynara
           cardunculus) Blanching Wastewater by Ultrafiltration—Study of
           Membrane Fouling and Flux Recovery after Chemical Cleaning

    • Authors: Garcia-Castello, Moratalla, Reig, Iborra-Clar, Iborra-Clar, Rodriguez-Lopez
      First page: 418
      Abstract: This study focused on the clarification of real blanching wastewaters from the industrial processing of cardoon, a plant rich in polyphenols and belonging to the artichoke family (Cynara cardunculus). The aim of this study was to evaluate the performance of ultrafiltration (UF) as an initial clarification step prior to a subsequent nanofiltration treatment for the recovery and fractionation of polyphenols from these wastewaters. In this UF process, three commercial UF membranes with different pore sizes: 3 kDa, 15 kDa, and 50 kDa. The assessment of the clarification process was based on two key factors: permeate flux and the concentration of phenolic compounds. The membrane with a MWCO of 3 kDa was excluded as a potential UF membrane due to its limited performance in terms of permeate flux. The 15 kDa membrane showed comparable results in terms of cumulative flux to the 50 kDa membrane. However, further evaluation based on fouling index and water permeability recovery favored the 15 kDa membrane, indicating better performance. To gain insights into the flux decline mechanisms and understand membrane fouling, a study was conducted on the 15 kDa and 50 kDa membranes. The analysis revealed that the cake filtration model provided the best fit for both membranes. The study highlights the potential of UF membranes, specifically the 15 kDa membrane, for the clarification of cardoon blanching wastewater.
      Citation: Separations
      PubDate: 2023-07-24
      DOI: 10.3390/separations10070418
      Issue No: Vol. 10, No. 7 (2023)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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