Subjects -> CHEMISTRY (Total: 986 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (713 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (47 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (713 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 29)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 9)
ACS Catalysis     Hybrid Journal   (Followers: 51)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 21)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Macro Letters     Hybrid Journal   (Followers: 25)
ACS Materials Letters     Open Access   (Followers: 2)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 43)
ACS Nano     Hybrid Journal   (Followers: 189)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 28)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 8)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 7)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 70)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 3)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 1)
Advanced Science Focus     Free   (Followers: 5)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 2)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 104)
Advances in Chemical Science     Open Access   (Followers: 50)
Advances in Chemistry     Open Access   (Followers: 34)
Advances in Chemistry     Full-text available via subscription   (Followers: 4)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 16)
Advances in Environmental Chemistry     Open Access   (Followers: 9)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 31)
Advances in Nanoparticles     Open Access   (Followers: 17)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 50)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 16)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 5)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 6)
Aggregate     Open Access   (Followers: 1)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 3)
Alchemy : Jurnal Penelitian Kimia     Open Access  
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 43)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 19)
American Journal of Chemistry     Open Access   (Followers: 37)
American Journal of Plant Physiology     Open Access   (Followers: 7)
Analyst     Hybrid Journal   (Followers: 36)
Analytical Science Advances     Open Access   (Followers: 1)
Angewandte Chemie     Hybrid Journal   (Followers: 152)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 226)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 6)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 14)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7)
Applied Surface Science     Hybrid Journal   (Followers: 30)
Arabian Journal of Chemistry     Open Access   (Followers: 4)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 2)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 2)
Atomization and Sprays     Full-text available via subscription   (Followers: 7)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 7)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 201)
Biochemistry Research International     Open Access   (Followers: 5)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access  
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 22)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 3)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 93)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 66)
Bioorganic Chemistry     Hybrid Journal   (Followers: 9)
Biopolymers     Hybrid Journal   (Followers: 15)
Biosensors     Open Access   (Followers: 3)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 5)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 5)
Carbohydrate Polymer Technologies and Applications     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Carbohydrate Research     Hybrid Journal   (Followers: 24)
Carbon     Hybrid Journal   (Followers: 65)
Carbon Capture Science & Technology     Open Access   (Followers: 5)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 9)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 11)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 8)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
Chem     Hybrid Journal   (Followers: 7)
Chem Catalysis     Hybrid Journal   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 21)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Hybrid Journal   (Followers: 81)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 25)
Chemical Physics Impact     Full-text available via subscription   (Followers: 5)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 174)
Chemical Science     Open Access   (Followers: 39)
Chemical Science International Journal     Open Access  
Chemical Technology     Open Access   (Followers: 74)
Chemical Thermodynamics and Thermal Analysis     Open Access   (Followers: 7)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 4)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 54)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 21)
ChemInform     Hybrid Journal   (Followers: 5)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Industry     Full-text available via subscription   (Followers: 6)
Chemistry - A European Journal     Hybrid Journal   (Followers: 123)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 19)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 17)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 6)
Chemistry Education Review     Open Access   (Followers: 1)
Chemistry in Education     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 5)
Chemistry of Materials     Hybrid Journal   (Followers: 159)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Hybrid Journal   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access  
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal   (Followers: 1)
Chemistry–Methods     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 2)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 13)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPhysMater     Full-text available via subscription   (Followers: 6)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access  
ChemSystemsChem     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal   (Followers: 1)
CHIMIA International Journal for Chemistry     Open Access   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 9)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 4)
Ciencia     Open Access  
Clay Minerals     Hybrid Journal   (Followers: 7)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 6)
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 2)
Combustion Science and Technology     Hybrid Journal   (Followers: 26)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 1)
Communications Chemistry     Open Access   (Followers: 2)
Communications Materials     Open Access  
Composite Interfaces     Hybrid Journal   (Followers: 6)
Comptes Rendus : Chimie     Open Access  
Comptes Rendus : Physique     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 11)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 13)
Computational Chemistry     Open Access   (Followers: 4)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 11)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 6)
Corrosion Communications     Open Access   (Followers: 5)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 17)
Croatica Chemica Acta     Open Access  
CrystEngComm     Hybrid Journal   (Followers: 10)

        1 2 3 4 | Last

Similar Journals
Journal Cover
Chromatographia
Journal Prestige (SJR): 0.514
Citation Impact (citeScore): 1
Number of Followers: 22  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1612-1112 - ISSN (Online) 0009-5893
Published by Springer-Verlag Homepage  [2469 journals]
  • Tea Component Analysis: From Chromatography Raw Data to a Fully Automated
           Report

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      Abstract: This paper presents a program to automatize many repetitive manual tasks needed to analyze data from a chromatography of tea samples. We present and explain the main steps of the code altogether with the process in which how raw data are gradually converted into figures and tables and finally a summarized report with them. Our main object was to enable researches to focus on data interpretation and discussion, then manually copying, pasting, and picking this or that set of data and inserting in this or that software to report and organize results. Our code can do in almost 1 h the amount of laborious work that would take a single researcher a whole week to be done.
      PubDate: 2022-01-20
       
  • Congress, Conferences, and Workshops

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      PubDate: 2022-01-19
       
  • Kinetic Degradation Study of Ipragliflozin Coupled with MS/MS Structural
           Elucidation

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      Abstract: Ipragliflozin degradation behavior was studied under different conditions: acidic, basic, photolytic, oxidative and thermal degradation conditions. This forced degradation study showed the extensive degradation of Ipragliflozin under acidic, basic and oxidative conditions while showed high stability under thermal and photo-degradation conditions. The separation of Ipragliflozin and its degradation products was done using Hypersil Gold® UPLC C18 column with 1.9 μm particle size (3 × 50 mm) as stationary phase and a mobile phase composed of acetonitrile: potassium monobasic phosphate buffer pH 3 (50:50; v/v) delivered at flow rate of 0.6 mL min−1. Validation of the proposed method was carried out in accordance to the International Council for Harmonisation’s guidelines. The method was found to be linear within the concentration range 5.0–50.0 µg mL−1 with a limit of detection of 1.48 µg mL−1. Accuracy was proven as the percentage recovery was 98.57 ± 0.40 and the percentage relative standard deviation was 0.82 which ascertained the precision. After chromatographic separation, mass characterization was used to structurally elucidate the degradation products and to propose the degradation pathway. Kinetics parameters of oxidative, acidic and basic degradation processes were determined and it was demonstrated that the degradation appears to follow a pseudo-first-order reaction. The simplicity and sensitivity of the proposed method promote its regular use in quality control laboratories. Graphical
      PubDate: 2022-01-15
       
  • Miniaturized Analysis of Methylhexanamine in Urine by Gas Chromatography
           Applying In Situ Derivatization

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      Abstract: The use of stimulants by professional and amateur athletes, as well as in the general population, to enhance their athletic performance represents a human health hazard. Methylhexaneamine (MHA) is a stimulant found in numerous dietary supplements and detected frequently in urine samples. The analytical process accepted by most Drug Testing Programs that employ urine use two methods, the first is an initial screening test, followed by a more specific method for the confirmation of presumptive positive urine specimens. For this reason, two specific analytical methods were developed and validated to determine MHA in urine based on its in situ derivatization with isobutyl chloroformate; the first was salting out assisted liquid–liquid extraction (SALLE) with gas chromatography coupled to mass spectrometry (GC–MS) and the second headspace solid-phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detector (GC–FID). Both methods were evaluated for precision (relative standard deviation < 10%), linearity (r2 > 0.98), accuracy at two concentration levels (recovery > 92%) and limit of detection (5–7 ng mL−1). The methods were successfully applied to analyze athletes’ urine samples from Comisión Nacional de Cultura Física y Deporte (CONADE, Mexico). The proposed methodologies are sensitive, precise, accurate, fast, and miniaturized, and they are suitable specific methods to analyze MHA in urine for anti-doping or forensic purposes even with an affordable GC–FID system.
      PubDate: 2022-01-15
       
  • C18 Reversed-Phase Liquid Chromatography Column Coupled with Ion
           Chromatography: a Method for the Determination of Trimethylamine
           Hydrochloride Residues in Cationic Etherifying Agent

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      Abstract: This method demonstrated an ion chromatography (IC) technique with suppressed conductance for the determination of residual trimethylamine hydrochloride (TMAC) in the synthesis of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC). The key point is the silicon-based C18 reversed-phase liquid chromatography column coupled with ion suppression chromatography for analysis. Due to the matrix of CHPTAC having a significant effect on the accuracy of ion chromatography (IC) determination, a standard addition method was used to calculate the influence of the matrix in CHPTAC samples on the accuracy of detection substances. The detection limit of this method was 0.1 μg mL−1 (signal to noise, S/N = 3), and the recovery of standard addition of TMAC was in the range 98.0–102.0%. The relative standard deviation (RSD) ranged from 0.8 to 1.26%, which showed that this optimized method has a good measurement precision and demonstrates satisfactory reliabilities. The experimental results showed that using a C18 reversed-phase chromatographic column can significantly reduce the problem of IC being susceptible to matrix effects and significantly improve the detection sensitivity of IC on the detection of TMAC in CHPTAC.
      PubDate: 2022-01-13
       
  • A Critical N-Nitrosamine Impurity of Anticoagulant Drug, Rivaroxaban:
           Synthesis, Characterization, Development of LC–MS/MS Method for Nanogram
           Level Quantification

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      Abstract: Background and Purpose The product recall for detecting unacceptable levels of carcinogenic potential N-nitrosamine impurities has been a severe apprehension in recent years. The regulatory agencies issued guidelines for the pharmaceutical industries to monitor nitrosamine impurities in the drug products. In the present study, we have been developed a robust, simple and sensitive ultra-high-performance liquid chromatography (UHPLC) coupled with mass spectrometry (LC–MS/MS) method for the determination of possible N-nitrosamine impurity, N-(2-hydroxyethyl)-N-phenylnitrous amide in the drug molecule, Rivaroxaban at nanogram level. Methods Chromatographic experiments were optimized on VD-Spher100 C18 E (150 mm × 4.6 mm, 3 μm) column, mobile phase flow was operated in isocratic mode using 0.1% aqueous formic acid and methanol in the ratio of 1:1 (v/v) with a flow rate of 0.6 mL/min, and column oven temperature maintained at 40 °C. The developed method was validated by following Q2(R1) International Conference on Harmonization” (ICH) guidelines. Results The limit of detection (LOD) and quantification (LOQ) of this N-nitrosamine impurity was 0.045 ng mL−1 and 0.15 ng mL−1, respectively. The accuracy and precision of the method were found well within the specified range. In addition, the synthesis and characterization details of N-nitrosamine impurity, N-(2-hydroxyethyl)-N-phenylnitrous amide were provided. Conclusions The developed method was applied well to determine N-nitrosamine impurity in bulk-scale samples of Rivaroxaban, revealing that the method could be worthwhile to use in the analysis of pharmaceutical dosage forms.
      PubDate: 2022-01-13
       
  • Gradient Polymer Elution Chromatography (GPEC): Under-Estimated Powerful
           Tool for Polymer Characterization—A Perspective

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      Abstract: Gradient polymer elution chromatography (GPEC) is a reliable polymer separation method applied in many polymer labs. For many polymer researchers and HPLC users, GPEC is an unknown separation method. However, many of the basic rules regarding polarity of solvents, polymers and stationary phases of traditional HPLC are applicable also in GPEC. The main differences are based on the nature of high molar mass polymers, limited solubility and a molar mass distribution.
      PubDate: 2022-01-09
       
  • Peak Fraction Purity and Chromatographic Resolution: Gaussian Peaks
           Revisited

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      Abstract: For incompletely resolved peak pairs, the purity of the chromatographic or fractographic fractions is oftentimes underestimated by the common user. This results in wasted time and effort while trying to achieve higher resolution than needed for the intended use. While a choice regarding acceptable fraction purity is ultimately up to the user and will be dictated by the purpose for which the separation is being conducted, knowledge of fraction purity as a function of chromatographic resolution Rs can help make an informed decision in this regard. To this effect, we revisit here the relationship between peak fraction purity and Rs for pairs of Gaussian peaks, equal pairs ranging in Rs from 0.42 to 1.68 and unequal pairs of various analyte ratios and Rs values. Employing sophisticated yet highly accessible commercial software, we calculate, to a greater precision than previously reported, the purity resultant from midpoint or valley cuts of peak pairs, and also show the improvement gained from performing these cuts at either the maxima of the cumulative peak or at the locations in this peak corresponding to the centers of gravity of the individual component peaks. The methodology employed and equations given are applicable to Rs values other than those investigated here and can be employed to calculate cut-point estimates for virtually any arbitrary desired purity.
      PubDate: 2022-01-08
       
  • Selective Separation of Polar Unsaturated Organics Using a Water
           Stationary Phase in Gas Chromatography

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      Abstract: A water stationary phase is explored as a novel means of selectively separating unsaturated analytes in gas chromatography. Several unsaturated/saturated analyte pairs consisting mainly of carboxylic acids and alcohols were examined using both a 30-m conventional non-polar HP-5 column and an 11-m water phase column. For most investigated on the HP-5 column, analytes often eluted very close to each other (~ 6–12 s apart) with poor resolution. By comparison, the shorter water phase column well separated each of the analogue pairs by about 3–8 min or more. As well on the water phase, analytes with a triple bond were much more retained than those with two double bonds, which in turn were much more retained than those with one double bond. Conversely, on the HP-5 column these were poorly separated if at all. Additionally, cis/trans isomers were baseline resolved on the water phase but co-eluted on a 30-m conventional polar Carbowax column. Similarly, positional isomers varying the location of the double bond were found to separate with a selectivity value near 1.1 on the Carbowax column, whereas on the water phase column they yielded a value of 1.3 and eluted in the reverse order. Addition of various metal ion salts to the water phase was explored. While Ca2+ ion produced modest increases in selectivity, the addition of Ag+ ion was most influential and further increased the original water phase selectivity by a factor of 2.3. The mechanistic implications of OH–-pi bonding in the water phase was discussed as a potential origin for the selectivity observed. The method was applied to gasoline, essential oil, and food stuff analysis. Results indicate that this method could be a very useful means of selectively separating such unsaturated analytes. Graphical abstract
      PubDate: 2022-01-06
       
  • Impact of HILIC Amino-Based Column Equilibration Conditions on the
           Analysis of Chitooligosaccharides

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      Abstract: Obtaining well-defined Chitooligosaccharides (COS) structures is very important as their physicochemical and biological properties depends strongly on their degree of polymerization (DP) and degree of N-acetylation (DA). Hydrophilic Interaction Liquid Chromatography (HILIC), that is commonly used for COS analyses, suffers from several drawbacks, related to their complex structure, leading to broadening/splitting of the chromatogram signals. We investigated, herein, on the role of the equilibration step of an amino-based HILIC column on the separation of COS DP ≤ 5. We demonstrated that COS could be separated according to their DP after equilibrating the column by a NaHCO3 buffer solution (100 mM, pH = 10) and mild elution chromatographic parameters (neutral mobile phase, r.t.); or according to their DA after equilibrating the column by an NH4Ac buffer solution (50 mM, pH = 4.5). Also, the nature of the counterion of the column stationary phase was found to affect both retention times and signal profiles of analyzed COS.
      PubDate: 2022-01-06
       
  • Study on the Effect of Three CYP2C9 Variants on Drug–Drug Interaction
           Related to Six Drugs In Vitro by LC–MS/MS Method

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      Abstract: The influence of genetic polymorphism of metabolic enzymes on drug–drug interactions (DDI) should be thoroughly investigated owing to its remarkable effect on therapeutic treatments that are futile. Here, different from earlier articles focused on various CYP subfamilies and their isoforms, the effect of genetic polymorphs of a particular isoform, CYP2C9, was comprehensively studied. Using diclofenac as probe substrate, the influence of three CYP2C9 variants (CYP2C9*1, *2 and *3) on DDI was conducted from the measurement of inhibitory ability of six drugs towards three variants. A modified LC–MS/MS method according to former report was constructed for the determination of 4ʹ-hydroxydiclofenac in CYP2C9 enzyme incubation system and validated for accuracy, precision, linearity range within the acceptance criteria for regulatory guidelines. After selecting appropriate incubation time and enzyme concentration, the kinetic parameters of three CYP2C9 variants towards diclofenac were examined and half inhibitory concentrations (IC50) of six drugs towards three CYP2C9 variants were determined. IC50 of paroxetine and losartan towards CYP2C9*2 were almost threefold higher and 2.5-fold lower than that towards CYP2C9*1, respectively. IC50 of glibenclamide towards CYP2C9*3 was twofold more than that towards CYP2C9*1. Our results could offer effective guidelines for co-administration of these six drugs with various CYP2C9 substrates in individuals carrying variant CYP2C9 alleles, also broaden the application area of LC–MS/MS.
      PubDate: 2022-01-06
       
  • A New Ecological RP-HPLC Method for the Determination of Pitavastatin,
           Fenofibrate and Their Impurities in a Novel Fixed Dose Combination

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      Abstract: We developed a simple, rapid, ecological RP-HPLC method for the estimation of Pitavastatin (PIT), Fenofibrate (FEN), and their impurities in a novel fixed dose combination. We achieved an efficient chromatographic separation in gradient elution mode using Hypersil BDS C18 (100 × 4.6 mm, 3.0 μm) column. The mobile phase A consisted of 0.1% glacial acetic acid buffer and mobile phase B consisted of ethanol and the flow rate was 1.7 mL per minute. We monitored the chromatogram at 250 nm detection wavelength and the column thermostat at 35 °C. The observed resolution for PIT, FEN, and 12 impurities is more than 1.5 for any pair of compounds. The proposed method was validated as per the ICH guidelines for precision, specificity, accuracy, linearity, robustness, ruggedness and it is efficient in estimating PIT, FEN, and their impurities in the same run. The drug product was subjected to various stress degradation conditions and observed a significant amount of degradation in hydrolytic and thermal degradation study. We estimated the method greenness using different Green Analytical Chemistry (GAC) metrics such as Analytical Eco-scale, scoring of hazardous values, Analytical Method Volume Intensity (AMVI), Environmental Assessment Tool (EAT), solvent selection guide approach, and Eco-solvent approach.
      PubDate: 2022-01-04
       
  • Porous Membrane-Assisted Purge and Trap Sampling for Determination of VOCs
           in Gas Chromatography with Needle-Type Extraction Device

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      Abstract: An analytical method using a porous polytetrafluoroethylene (PTFE) membrane that passes through gas while repelling water, and a needle-type extraction device was developed for purge-and-trap (PT) extraction followed by gas chromatography–mass spectrometric (GC–MS) determination of volatile organic compounds (VOCs) in water samples. The PTFE membrane was fixed in a solid-phase extraction glass cartridge, and 10 mL of water sample and sodium chloride were added. Then, a needle-type extraction device was inserted into the cartridge headspace, and the headspace gas was collected. Due to decompression on the inside of the cartridge, purge gas was introduced from the bottom side of the cartridge through the PTFE membrane. After the sample extraction, VOCs were thermally desorbed by inserting the needle into the heated GC injection port. The limit of quantification of the proposed method for 23 investigated VOCs was less than 0.5 μg/L, and the upper limit of the calibration curve was 500 μg/L for dichloromethane and 1000 μg/L for other compounds. The relative standard deviations of the relative peak area for 23 investigated VOCs were less than 15% (n = 5). The method was used to determine VOCs in tap water samples.
      PubDate: 2022-01-01
       
  • Built-in Chamber-Coupled Electronic Pressure Control of Ambient Air as the
           Carrier Gas for a Cylinder-Free Portable Gas Chromatograph

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      Abstract: An electronic pressure control unit, coupled with a small built-in compressed air chamber, is applied to a field-portable gas chromatograph to precisely adjust the column head pressure with an accuracy of < 0.04% relative standard deviation. This system features a repetitive refill design of ambient air as the carrier gas through the use of a small diaphragm pump, thereby eliminating the need for external gas supplies or disposable cylinders. The flow rate of the separation column determined from the consumption rate of the air chamber matches exactly with the results of holdup time measurements of an unretained peak, as well as theoretical flow calculations within a 2% relative standard deviation. Mixtures of aromatic volatile organic compounds were then analyzed to demonstrate the performance of the built-in chamber-coupled electronic pressure control system. A 30 m × 0.28 mm × 1.0 μm capillary column operated at an isothermal temperature of 70 ℃ and an inlet pressure of 12 psig above atmospheric pressure provided a peak capacity of 60 with an analysis time of < 10 min for a vapor mixture of benzene, toluene, ethylbenzene, and o-xylene. The measurement cycle, including sample collection, injection, separation, and detection required a total time of only 15 min. The relative standard deviations of the retention time and the peak intensity variation during 40 h of operation were < 0.19% and < 0.74%, respectively, demonstrating the reproducibility and long-term stability of this process for continuous measurements. Such temperature programming of the constant head pressure and control of the flow rate ultimately allows faster analysis with very little peak broadening of the long retention peaks.
      PubDate: 2022-01-01
       
  • Method Improvement for Analysis of Enrofloxacin and Ciprofloxacin in
           Chicken Meat: Application of In-Sample Addition of Trace
           Ethylenediaminetetraacetic Acid to Isotope Dilution Ultra-Performance
           Liquid Chromatography–Mass Spectrometry

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      Abstract: A method for analyzing fluoroquinolone antibiotics, viz. enrofloxacin and ciprofloxacin, in chicken meat has been developed with the aim of reducing the total analysis time. Certified reference materials (CRMs) for the chicken meat powder, i.e. KRISS CRM 108-03-003 and KRISS CRM 108-03-004, were used for method development. Isotope dilution ultra-performance liquid chromatography–mass spectrometry (ID-UPLC-MS) was employed for sample analysis. The liquid chromatography (LC) conditions were optimized with an “in-sample addition” method using a trace amount of ethylenediaminetetraacetic acid (EDTA), in which EDTA was not added to the mobile phase but to the sample alone. The optimal EDTA amount was determined, and its influence on the separation of the target analyte was investigated. After the feasibility of the “in sample-addition” approach was confirmed, we attempted to improve the previously established sample pretreatment method by varying the conditions for liquid–liquid extraction and solid phase extraction. The developed method was validated using raw chicken meat for recovery evaluation. The “in-sample addition” method afforded highly improved peak shapes without adversely affecting the LC/MS method performance, and the quantification values of enrofloxacin and ciprofloxacin corresponded well with those obtained using the established method. Consequently, the total analysis time for the determination of enrofloxacin and ciprofloxacin in chicken meat CRM could be reduced by simplifying the sample pretreatment procedure. The developed method delivered better reliability compared to the previously established analytical method. The method will be used for stability monitoring of the chicken meat CRM and the development of other meat CRMs for fluoroquinolone analysis and improved food safety applications.
      PubDate: 2022-01-01
       
  • Multiwalled Carbon Nanotubes-Encapsulated Gellan Gum Membrane for
           Micro-Solid Phase Extraction of Selected Polycyclic Aromatic Hydrocarbons
           in Environmental Water and Beverages

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      Abstract: Non-biodegradable plastics are an unresolved issue in solid waste management as recycling them is expensive. This study focused on formulating a biodegradable gellan gum (GG) membrane embedded with multiwalled carbon nanotubes (MWCNTs) as the adsorbent in the micro-solid phase extraction (µ-SPE) of selected polycyclic aromatic hydrocarbons (PAHs), i.e. phenanthrene, fluoranthene, pyrene and benzo[a]pyrene, in environmental water and fruit-juice beverage samples. PAHs quantitation was performed using micro-high-performance liquid chromatography coupled with ultraviolet detection. The MWCNTs GG membrane was fabricated by mixing MWCNTs in a hot GG solution, which was then crosslinked with glutaraldehyde to resist membrane swelling during extraction. Under the optimal extraction conditions, the proposed µ-SPE technique demonstrated good linearity (1–500 µg L−1; correlation coefficient of ≥ 0.9925) and ultra-trace detection limits (10–60 ng L−1). Good relative recoveries in the range of 81.3–114.9% with acceptable relative standard deviations (≤ 9.7%) revealed that matrix effects were insignificant because the MWCNTs-GG membrane-based µ-SPE offered a clean extract in these real samples. The proposed µ-SPE technique is proven to be sensitive, accurate and green with an analytical eco-scale score of 81, which supports green analysis for a better tomorrow. Graphical
      PubDate: 2022-01-01
       
  • Oligosaccharide Profile Analysis and Quality Control of Atractylodes
           macrocephala Koidz. Using HPLC-HRMS/MS and a Simple HPLC-ELSD Method

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      Abstract: Oligosaccharides in Atractylodes macrocephala Koidz. (AMK) have a wide range of clinical effects, especially in terms of improving immunity. In this study, the oligosaccharide fingerprint of AMK was first established by high-performance liquid chromatography coupled with evaporative light-scattering detection. This method was confirmed to be accurate and reliable. Twenty-six batches of samples from four regions were detected, and the oligosaccharide fingerprint similarity of AMK was evaluated (> 0.900). Second, the oligosaccharide profile of AMK was analyzed using high-performance liquid chromatography coupled to high-resolution tandem mass spectrometry. Fourteen inulin-type oligosaccharides with a degree of polymerization of 2–15 were identified, including sucrose, 1-kestose, and nystose. Finally, two representative compounds, 1-kestose and nystose, were selected for quantification analysis. The established method had good regression equations, precision, repeatability, and stability. The average contents of 1-kestose and nystose were 0.688% and 0.827%, respectively. This study provides valuable information on the quality evaluation and discrimination of different varieties of AMK.
      PubDate: 2022-01-01
       
  • Congress, Conferences, and Workshops

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      PubDate: 2021-12-01
       
  • Use of Tetrabutylammonium Bromide and l-Arginine-Based Deep Eutectic
           Mixture in Combination with Beta-Cyclodextrin for Chiral Discrimination of
           Amino Acids in Capillary Electrophoresis

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      Abstract: The potential effects of deep eutectic solvents (DESs) based on eutectic mixtures of amino acids (AAs) and tetrabutylammonium bromide (TBABr) in combination with beta-cyclodextrin (β-CD) were first evaluated as chiral systems in capillary electrophoresis (CE). Three DESs: tetrabutylammonium bromide/l-arginine (TBABr/l-Arg), tetrabutylammonium bromide/l-alanine (TBABr/l-Ala) and tetrabutylammonium bromide/l-proline (TBABr/l-Pro)) were used. Markedly improved chiral discrimination for four native amino acids (dl-methionine, dl-valine, dl-serine and dl-threonine) were obtained with high resolutions ranging from 4.78 to 9.84 in the presence of TBABr/l-Arg/β-CD chiral selector. Optimal CE conditions were a BGE containing 15 mmol L−1 β-CD and 10% (v/v) TBABr/l-Arg mixed with 50 mmol L−1 borate at pH 9.5, 20 kV applied voltage and 25 °C capillary temperature. The relative standard deviations (RSDs) of intra- and inter-day variations of migration times were less than 2.2% and 3.5%, respectively. l-Arg has the highest isoelectric point (pI = 10.7 at 25 °C) among protein amino acids which is appropriate for formation of stable DES at an alkaline separation medium. Moreover, TBABr/l-Arg/β-CD possessed the lowest electroosmotic flow velocity (0.018 cm2 min−1 V−1) among the investigated chiral systems providing more opportunities for chiral recognition of analytes within 14 min. Analytical characteristics of the CE/UV developed method were evaluated and demonstrated to be adequate to apply the methodology to enantiomeric analysis of methionine in commercial dietary supplements including enantiomeric impurity of d-methionine at 0.03% level (m/m). Therefore, the proposed TBABr/l-Arg/β-CD could be used as a versatile, simple and effective selector for baseline chiral recognition in CE.
      PubDate: 2021-12-01
       
  • Congress, Conferences, and Workshops

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      PubDate: 2021-11-29
       
 
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