Subjects -> CHEMISTRY (Total: 1001 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (726 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (49 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (726 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
Accounts of Materials Research     Hybrid Journal  
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 36)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 15)
ACS Catalysis     Hybrid Journal   (Followers: 78)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 25)
ACS Combinatorial Science     Hybrid Journal   (Followers: 25)
ACS Macro Letters     Hybrid Journal   (Followers: 34)
ACS Materials Letters     Open Access   (Followers: 4)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 49)
ACS Nano     Hybrid Journal   (Followers: 452)
ACS Photonics     Hybrid Journal   (Followers: 19)
ACS Symposium Series     Full-text available via subscription   (Followers: 3)
ACS Synthetic Biology     Hybrid Journal   (Followers: 40)
Acta Chemica Iasi     Open Access   (Followers: 8)
Acta Chemica Malaysia     Open Access  
Acta Chimica Slovaca     Open Access   (Followers: 4)
Acta Chimica Slovenica     Open Access   (Followers: 2)
Acta Chromatographica     Full-text available via subscription   (Followers: 9)
Acta Facultatis Medicae Naissensis     Open Access   (Followers: 1)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 10)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 10)
Adsorption Science & Technology     Open Access   (Followers: 9)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 81)
Advanced Journal of Chemistry, Section A     Open Access   (Followers: 15)
Advanced Journal of Chemistry, Section B     Open Access   (Followers: 14)
Advanced Science Focus     Free   (Followers: 7)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 5)
Advanced Therapeutics     Hybrid Journal   (Followers: 1)
Advances in Chemical Engineering and Science     Open Access   (Followers: 108)
Advances in Chemical Science     Open Access   (Followers: 50)
Advances in Chemistry     Open Access   (Followers: 39)
Advances in Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21)
Advances in Drug Research     Full-text available via subscription   (Followers: 27)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
Advances in Enzyme Research     Open Access   (Followers: 13)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 20)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 35)
Advances in Nanoparticles     Open Access   (Followers: 20)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 20)
Advances in Polymer Science     Hybrid Journal   (Followers: 54)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 22)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7)
Advances in Science and Technology     Full-text available via subscription   (Followers: 17)
Aerosol Science and Engineering     Hybrid Journal  
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 6)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Aggregate     Open Access   (Followers: 3)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 3)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 5)
Alchemy : Jurnal Penelitian Kimia     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Alotrop     Open Access  
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 71)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 24)
American Journal of Chemistry     Open Access   (Followers: 41)
American Journal of Plant Physiology     Open Access   (Followers: 13)
Analyst     Full-text available via subscription   (Followers: 40)
Analytical Science Advances     Open Access   (Followers: 2)
Angewandte Chemie     Hybrid Journal   (Followers: 237)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 354)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 8)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 4)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 6)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 13)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 16)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 12)
Applied Spectroscopy     Full-text available via subscription   (Followers: 27)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Applied Chemistry Research     Open Access   (Followers: 2)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemical Sciences     Open Access   (Followers: 1)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Asian Journal of Physical and Chemical Sciences     Open Access   (Followers: 3)
Atomization and Sprays     Full-text available via subscription   (Followers: 8)
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: 486)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 3)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 4)
Biomacromolecules     Hybrid Journal   (Followers: 27)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 11)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 4)
BioNanoScience     Partially Free   (Followers: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 217)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 88)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 4)
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: 26)
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 Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 13)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Polymer Technologies and Applications     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 13)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 76)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 9)
Catalysis Science and Technology     Hybrid Journal   (Followers: 13)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysts     Open Access   (Followers: 14)
Cell Reports Physical Science     Open Access  
Cellulose     Hybrid Journal   (Followers: 17)
Cereal Chemistry     Full-text available via subscription   (Followers: 6)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 3)
ChemCatChem     Hybrid Journal   (Followers: 11)
Chemical and Engineering News     Free   (Followers: 24)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 88)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 28)
Chemical Physics Letters : X     Open Access   (Followers: 4)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 4)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 25)
Chemical Reviews     Hybrid Journal   (Followers: 267)
Chemical Science     Open Access   (Followers: 44)
Chemical Science International Journal     Open Access   (Followers: 1)
Chemical Technology     Open Access   (Followers: 71)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 23)
ChemInform     Hybrid Journal   (Followers: 9)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 31)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 225)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 20)
Chemistry Africa : A Journal of the Tunisian Chemical Society     Hybrid Journal  
Chemistry and Materials Research     Open Access   (Followers: 24)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry Education Research and Practice     Free   (Followers: 8)
Chemistry Education Review     Open Access   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry Letters     Full-text available via subscription   (Followers: 49)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 338)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 20)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
ChemistrySelect     Hybrid Journal  
Chemistry–Methods     Open Access   (Followers: 2)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
ChemNanoMat     Hybrid Journal   (Followers: 1)
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access   (Followers: 1)
ChemPhotoChem     Hybrid Journal  
ChemPhysChem     Hybrid Journal   (Followers: 14)
ChemPlusChem     Hybrid Journal   (Followers: 2)
Chempublish Journal     Open Access   (Followers: 1)
ChemSystemsChem     Hybrid Journal   (Followers: 2)
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: 13)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Ciencia     Open Access   (Followers: 1)
Clay Minerals     Hybrid Journal   (Followers: 9)
Cogent Chemistry     Open Access   (Followers: 3)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 12)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 8)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 4)
Combustion Science and Technology     Hybrid Journal   (Followers: 25)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)

        1 2 3 4 | Last

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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  [2658 journals]
  • Liquid Chromatography Analysis of Reactive Oxoammonium Cations

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      Abstract: This study presents the first liquid chromatography method for the quantitative and qualitative analysis of highly reactive oxoammonium cations based on a simple derivatization reaction. Rapid 1,2-electrophilic addition reactions with olefins were used to transform these reactive species into analyzable derivates. Three model substances were chosen to represent each of the main application fields of oxoammonium cations and to demonstrate the versatility of the method. The measuring protocol was validated according to the ICH and USP guidelines. The method revealed an excellent linearity (R2 = 0.9980–0.9990) with a low limit of detection (0.16–0.14 mmol L−1) and a low limit of quantification (0.55–0.43 mmol L−1). The protocol was finally used to determine the oxoammonium cations in the presence of their corresponding radical, showing a robustness against impurity concentration of up to approx. 30%.
      PubDate: 2021-11-01
       
  • Simultaneous Determination of 16 Illegally Added Drugs in Capsule Dietary
           Supplements Using a QuEChERS Method and HPLC–MS/MS

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      Abstract: A simple and rapid method based on the QuEChERS (quick, easy, cheap, effective, rugged, and safe) pretreatment and HPLC–MS/MS (high performance liquid chromatography–tandem mass spectrometry) system was successfully developed and validated for the analysis of 16 illegally added chemical drugs in capsule dietary supplements for weight-loss and lipid reduction. Samples were extracted with acetonitrile solution containing 1% formic acid. Then 500 mg mixed anhydrous magnesium sulfate and sodium chloride (1:1; m/m) were used for salting out, and 100 mg PSA adsorbents were used for purification. 16 analytes rendered good linearity in the range of 0.025–20 μg/g. The limits of detection (LOD) and limits of quantitation (LOQ) ranged from 0.3 to 20 ng/g and 1 to 50 ng/g, respectively. All the linear correlation coefficients were greater than 0.9942. The accuracy values of 16 analytes were between 80.21 and 118.35%, and the stability expressed by relative standard deviations (RSDs) were < 11.06% within three adding levels. Finally, fluoxetine was detected in 2 batch samples by the method. This method is simple, fast, practical and suitable for rapid detection of illegally added drugs in dietary supplements for weight loss and fat reduction. It also provides more powerful technical supports for the supervision of dietary supplements safety and can be used as an analytical method for the detection of such illegally added substances.
      PubDate: 2021-11-01
       
  • Rapid Profiling of Chemical Constituents in Qingfei Paidu Granules Using
           High Performance Liquid Chromatography Coupled with Q Exactive Mass
           Spectrometry

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      Abstract: Qingfei Paidu (QFPD) granules have played a critical role during the Coronavirus Disease 2019 (COVID-19) in China. However, worldwide acceptance has been a problem because of the complex ingredients and unique theory of treatment. In this study, high-performance liquid chromatography (HPLC)-Q Exactive Orbitrap-mass spectrometry (MS) and the Orbitrap traditional Chinese medicine library (OTCML) were used to investigate the chemical constituents of QFPD granules. By comparing retention times, masses, isotope ion patterns, and MS2 profiles, 108 compounds were putatively identified using the OTCML combined with manual verification, including 12 alkaloids, 49 flavonoids, 13 terpenoids, 14 phenylpropanoids, 4 phenolic acids, 5 phenols, and 11 other phytochemicals. Of these compounds, 17 were confirmed using reference standards. In addition, representative compounds of these different chemical types were used as examples to analyze the fragmentation pathways and characteristic product ions. Moreover, 20 herbs within the QFPD granules were also identified to establish the sources of these chemical components. This is the first rapid profiling of the chemical constituents of QFPD granules using HPLC-Q Exactive Orbitrap-MS and yields valuable information for further quality control and mechanistic studies of QFPD granules.
      PubDate: 2021-11-01
       
  • UPLC Coupled with a Post-column Derivatization Approach for Identification
           of Bioactive Compounds in Huanglian Jiedu Decoction

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      Abstract: A UPLC coupled with post-column derivatization (PCD) and diode array detector (DAD) collecting biochemical reaction signal analysis technique (UPLC–PDC–DAD) was developed and applied to screen acetylcholinesterase (AChE) inhibitors, 1,1-diphenyl-2-picrylhydrazyl and 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radical scavengers in Huanglian Jiedu decoction (HLJDD) and its constituent herbs; The main active ingredients in the HLJDD were identified by UPLC–linear ion trap/orbitrap mass spectrometry; The twenty peaks showing obvious free radicals scavenging activity were mainly derived from Coptidis Rhizoma, Scutellariae Radix and Phellodendri Cortex in HLJDD. The five peaks in Coptidis Rhizoma and Phellodendri Cortex exhibiting strong AChE inhibition activity were identified as coptisine, epiberberine, jatrorrhizine, berberine and palmatine, respectively. Jatrorrhizine was found to possess radical scavenging and AchE inhibiting activities; The proposed UPLC–PCD–DAD method could identify rapidly and efficiently the different bioactivities of multiple components in complex matrixes and reveal the different mechanisms of the components in the treatment of some diseases.
      PubDate: 2021-11-01
       
  • Assay of Ivermectin Including Determination and Identification of Its
           Related Substances in Ivermectin Injectable Product by a
           Stability-Indicating RP-HPLC Method

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      Abstract: Ivermectin injectable product is widely used as a parasiticide for the treatment and control of internal and external parasites of cattle and swine. A reversed-phase high performance liquid chromatography (RP-HPLC) method has been developed for the assay of ivermectin, including the determination and identification of its related substances in an ivermectin injectable product. Ivermectin and its related substances are adequately separated using a gradient elution at a flow rate of 1.5 mL/min on a Zorbax Extend-C18 column (150 × 4.6 mm i.d., 3.5 µm particle size) maintained at 30 °C. Mobile phase-A is composed of water and mobile phase-B is composed of acetonitrile/methanol (85/15, v/v). Analytes were monitored by UV detection at 245 nm. The stability-indicating capability of the method has been demonstrated by adequately separating the degradation products from the stress degraded samples of the ivermectin injectable product. The analytical performance of the method was validated as per the current ICH guidelines with respect to specificity, linearity (R2 > 0.999), accuracy, precision, detection limit (0.3 µg/mL), quantitation limit (1.0 µg/mL), and robustness. This newly developed HPLC method for assay of ivermectin and determination of its related substances can be used to increase the throughput of a quality control (QC) lab for analytical testing of ivermectin injectable products.
      PubDate: 2021-11-01
       
  • 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: 2021-10-23
       
  • Gas Chromatography with Modified pH-Sensitive Pellets in Evaluating
           Esterase Activity of Carbonic Anhydrase III Enzyme: Drug Discovery
           Approach

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      Abstract: Antagonism of carbonic anhydrase, isozyme 3 (CAIII) has a strong potential in treating obesity, hyperlipidemia and cancer. The enzyme has a very low activity in hydrating carbon dioxide which makes it unresponsive to the majority of methods used against other CAs. In this study, a new evaluation method based on gas chromatography (GC) is considered for the screening of the inhibitory activity of various nicotinic acid derivatives against CAIII using immobilized pH-sensitive matrix pellets. The CA inhibitory activity of 14 nicotinic acid derivatives were studied using a GC method. The percentage of the inhibition of nicotinic acid derivatives against CA was calculated and found to be related to the molecular volume of the candidate inhibitor. This might be due to the limited size of CAIII’s active site. A lower molecular volume correlates with the inhibitory effect of each candidate. This approach of analysis might be utilized in developing sensitive GC methods for other enzymes attributed with pH change in their media. Particularly, for those which require accurate and sensitive assay methods.
      PubDate: 2021-10-22
       
  • Forced Degradation Studies of Sofosbuvir with a Developed and Validated
           RP-HPLC Method as per ICH Guidelines

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      Abstract: A reverse phase-high-performance liquid chromatography-diode array detector method is developed for the determination of the antiviral drug sofosbuvir in bulk and Sofos® 400 mg tablet dosage forms. Sofosbuvir is used for the treatment of chronic hepatitis C. The separation is carried out using a gradient mobile phase consisting of 0.05% H3PO4 and acetonitrile. A symmetry C18 column (4.6 × 100 mm, 2.5 µm, Waters XSELECT HSS T3) is used with a flow rate of 1.5 mL min−1 using ultraviolet detection at 260 nm with a diode array detector and an injection loop volume of 10 µL. A sharp peak is obtained at a retention time of 14 min. The method is validated appropriately according to the requirements of the United States Pharmacopeia and the International Conference on Harmonization guideline Q2 R1. System suitability, linearity, range (1.5–4.5 µg mL−1), precision, accuracy, specificity, robustness, detection and quantification limit of the method are assured. A forced degradation study of sofosbuvir is conducted under the conditions of hydrolysis, oxidation, thermal and photolysis.
      PubDate: 2021-10-18
       
  • Immobilized Kallikrein Microreactor Based on Capillary Electrophoresis for
           Online Enzyme Kinetics Analysis and Inhibitor Screening

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      Abstract: In this study, an online capillary electrophoresis-based immobilized enzyme microreactor (CE-IMER) was developed for evaluating inhibitory activity of small-molecule compounds and tea polyphenol extracts on kallikrein (KLK). KLK was immobilized on the inner wall at the inlet of capillary to prepare the KLK-IMER with the aid of chitosan and glutaraldehyde. The immobilized KLK activity and other kinetic parameters were evaluated by measuring the peak area of hydrolysate of chromogenic substrate S-2302 (H-D-Pro-Phe-Arg-pNA). The Michaelis–Menten constant (Km) was determined to be 1.82 mM, and the half-maximal inhibitory concentration (IC50) and inhibition constant (Ki) of nicotinamide (positive control drug) were measured to be 12.07 and 4.31 mM, respectively. The negative control drug tinidazole (5.00 mM) had no inhibitory effect on KLK. Moreover, the activity of the immobilized KLK remained approximately 80.0% of the initial immobilized enzyme activity after 30 runs. The CE-IMER was applied to investigate the inhibitory activity of 10 small-molecule compounds and six tea polyphenol extracts on KLK. The results show that four small-molecule compounds (epicatechin gallate, epigallocatechin, epicatechin and isochlorogenic acid C) (0.25 mM) and six polyphenol extracts (Raw Pu-erh, Mingqian Mao Feng, Fuding white tea, Dark green tea, Biluochun and Black tea) (0.25 mg mL−1) have high inhibitory activity on KLK. In addition, these four small-molecule compounds have binding energies below − 5.0 kcal mol−1 on KLK according to the molecular docking. In short, this study reports a time saving method (0.75 h) for KLK immobilization under mild conditions (25 °C). Graphic abstract
      PubDate: 2021-10-11
       
  • Liquid Chromatography at Critical Conditions in Polymer Analysis: A
           Perspective

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      Abstract: Liquid chromatography at critical conditions is one of the major chromatographic techniques for characterization of complex polymers beyond mere total molar mass. In this perspective, different approaches of analyses using critical conditions are elaborated. Strengths, opportunities, and caveats associated with different LCCC approaches are discussed. Finally, the future challenges and opportunities are highlighted.
      PubDate: 2021-10-05
       
  • Congress, Conferences, and Workshops

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      PubDate: 2021-09-29
       
  • Modeling and Optimization of Chromatographic Purification of Arglabin from
           CO2 Extract of Artemisia glabella Kar. et Kir.

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      Abstract: The dried aerial parts of the plant Artemisia glabella Kar. et Kir. contain about 1.1% of the very important sesquiterpene lactone arglabin. This compound can be extracted by supercritical CO2 giving a 20 time concentrated extract containing about 22% arglabin. The CO2 extract can be efficiently treated by hydrostatic countercurrent chromatography (CCC) able to produce in a single run 95% pure arglabin. Both mobile and stationary phase are liquid in CCC. The biphasic waterless liquid system heptane:ethyl acetate:acetonitrile 2:1:2 v/v/v was used to separate arglabin from its two major co-extracted compounds: argolide and eucalyptol. A three-factor Box–Behnken design was used to optimize the CCC preparative purification of the CO2 extract by a FCPC-5L instrument. Injected amount, mobile phase flow rate, and rotor rotation speed were used to optimize arglabin productivity. An optimized run was able to treat 90 g of extract producing 20 g of 95% pure arglabin in 50 min, a theoretical productivity of 400 mg/min.
      PubDate: 2021-09-18
      DOI: 10.1007/s10337-021-04093-0
       
  • Preparation of a Poly(2-thiopheneacetic acid) Coating on Magnetite
           Nanoparticles with One Single Carbon Layer (Fe3O4@1C NPs) for Selective
           Magnetic Solid-Phase Extraction of Canthin-6-one Alkaloids in Eurycoma
           longifolia

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      Abstract: We present a facile approach for the direct attachment of cross-linked poly(2-thiopheneacetic acid) onto the surface of magnetite nanoparticles with one single carbon layer (Fe3O4@1C NPs) via self-assembly oxidative polymerization. The functional Fe3O4@1C NPs combined with poly(2-thiopheneacetic acid) [Fe3O4@1C@ poly(Th) NPs] was successfully prepared and used for magnetic solid-phase extraction (MSPE). The influence of the preparation conditions and extraction conditions were investigated in detail. The morphology and size distribution of the monolithic materials were characterized by transmission electron microscopy. Under the optimized experimental conditions, the prepared Fe3O4@1C@ poly(Th) NPs showed good extraction efficiency for canthin-6-one alkaloids. Furthermore, the results indicated that the binding specificity and selectivity of the Fe3O4@1C@ poly(Th) NPs might be attributed to electrostatic interactions and pore structure. A MSPE–HPLC method was also developed for quantitative analysis of canthin-6-one alkaloids. The developed method showed good linearity, low limit of detections, low limit of quantifications, and good reproducibility over a wide linear range. To further prove the utility, Fe3O4@1C@ poly(Th) NPs-MSPE was also used to extract canthin-6-one alkaloids from Eurycoma longifolia stems, with a recovery rate of 87.9–114%. Thus, this method is potentially applicable for the extraction of similar alkaloid compounds from medicinal herb samples.
      PubDate: 2021-09-17
      DOI: 10.1007/s10337-021-04090-3
       
  • Online Column Extraction Coupled with Double-Trap Column System for HPLC
           Determination of Valproic Acid in Human Plasma Without Derivatization

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      Abstract: An automated online column extraction coupled with high-performance liquid chromatography (HPLC) and equipped with a double-trap column system was developed to determine valproic acid in human plasma without derivatization for routine therapeutic drug monitoring (TDM). 300 μL of plasma sample pretreated by precipitating the protein was injected into a Diamonsil C18 extraction column in the first focusing step. After the elution of the pretreated sample, the targets were transferred from the extraction column to a strong cation exchange trap column through “central cutting” mode in the second focusing step. Finally, the targets were transferred from the strong cation exchange trap column to reverse-phase C18 analytical column and were detected under an UV wavelength of 215 nm. In this method, the extraction system performs the sample injection, extraction, and transfer of targets from the extraction column to one trap column. Meanwhile, the analytical system performs the transfer of targets from other trap column to the analytical column, separation, and detection of targets. This method showed good linearity of calibration curve (R = 0.9999), precision (relative standard deviation (RSD) < 5.4%), and accuracy (within 5.6% in terms of relative error). Therefore, a promising approach was developed for routine monitoring of valproic acid concentration in human plasma.
      PubDate: 2021-09-14
      DOI: 10.1007/s10337-021-04089-w
       
  • Combination of Derivatization–HPLC–MS and Enzymatic Hydrolysis–Edman
           Degradation for Amino Acid Sequence and Configuration of Polymyxin B
           Components

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      Abstract: An analysis strategy that can simultaneously determine the amino acid site information and configuration for polymyxin (PM) components is reported in this study. The main components of PMB1, PMB2, and PMB1-I (the Leucine at position 7 changed to be Isoleucine) were purified from the mixture of PMB. The PMB component was hydrolyzed by hydrochloric acid to be a mixture of amino acids, which were derivatized with Marfey’s reagent of Nα-(5-fluoro-2,4-dinitrophenyl)-l-alanine amide (l-FDAA), and then, the configurations of amino acids were easily determined by HPLC–MS. However, the aforementioned method could not offer the information of amino acid at each site, a specific enzymatic hydrolysis method combined Edman degradation was developed. The fatty acyl-diaminobutyric acid (position 1) of PMB component was removed by ficin, and the PMB components were transformed to be PMB nonapeptide. The amino acids at each site of the nonapeptide were determined by N-terminal sequencing. Combining the results of the above methods, the amino acid information and configuration of each site in PM components can be determined, especially the l-Leucine and l-Isoleucine in PMB1 and PMB1-I. The workflow was useful for other PM analogues to identify the sequence and configuration for quality control.
      PubDate: 2021-09-14
      DOI: 10.1007/s10337-021-04091-2
       
  • Congress, Conferences, and Workshops

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      PubDate: 2021-08-30
      DOI: 10.1007/s10337-021-04086-z
       
  • Development and Validation of a Stability-Indicating RP-HPLC Method for
           Determination of Eprinomectin, its Degradation Products, and Butylated
           Hydroxytoluene in a Pour-On Finished Product

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      Abstract: Eprinomectin (EPM) is the active pharmaceutical ingredient (API) of the pour-on finished product. The finished product also contains propylene glycol octanoate decanoate (PGOD) as an excipient and solvent, and butylated hydroxytoluene (BHT) as an antioxidant. EPM belongs to a group of compounds known as avermectins and is commercially available as a mixture of two closely related homologues, namely, EPM B1a and EPM B1b. A stability-indicating reverse-phase high-performance liquid chromatography (RP-HPLC) method is developed and validated, which can provide data for EPM assay and estimation of its degradation products as well as the assay of BHT from the chromatogram of a single injection of the finished product sample. The new HPLC method uses a Halo-C18 column (100 mm × 4.6 mm i.d., 2.7 µm particle size) maintained at 40 °C with 100% Water (H2O) as Mobile Phase-A and Isopropanol(IPA)/Acetonitrile(ACN) (70/30, v/v) as Mobile Phase-B. Analytes are separated by a gradient elution with a total run time of 35 min. EPM and its degradation products except 8a-oxo-B1a are detected by UV at 245 nm while 8a-oxo-B1a and BHT are detected at 280 nm.
      PubDate: 2021-08-22
      DOI: 10.1007/s10337-021-04082-3
       
  • Micellar Electrokinetic Chromatographic Analysis of Historic Dyes and
           Their Photofading Products

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      Abstract: Since the early 20th century, the Monroe Chemical Company’s Putnam Fadeless Dyes were used by consumers to dye numerous types of textiles. In this work, we describe a novel micellar electrokinetic chromatographic (MEKC) method employing sodium cholate and acetonitrile in the background electrolyte that can be used to analyze these dyes. Specifically, Putnam Fadeless Dyes were successfully extracted from linen samples colored with them and the components of each dye were separated and detected using MEKC. These results compared favorably to MEKC data from standard dye solutions. Dyed linen samples were also exposed to simulated sunlight and MEKC was used to analyze dyes extracted from them. The resulting data showed that photofading altered the amount of dye in the fabric but not its chemical composition.
      PubDate: 2021-08-12
      DOI: 10.1007/s10337-021-04080-5
       
  • Combined Application of Macroporous Resins and Preparative
           High-performance Liquid Chromatography for the Separation of Steroidal
           Saponins from Stems and Leaves of Paris polyphylla

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      Abstract: In this study, the combined techniques of macroporous resin column chromatography and preparative high-performance liquid chromatography were applied for the separation of steroidal saponins from the stems and leaves of Paris polyphylla. Eight types of macroporous resins were examined using adsorption and desorption tests. Resin HPD-600 showed the maximum effectiveness and thus was selected for the first cleaning-up, in which 30% ethanol was used to remove the undesired constituents and 90% ethanol was used to elute the targets. Paris saponin II (36.2 mg) and dioscin (14.0 mg) were obtained from 500.5 mg of the extracts after purification by preparative high-performance liquid chromatography, with purities above 95% and yields of 81.87 and 72.89%, respectively. These results suggest that combined strategy is a useful and economic method to enrich and purify steroidal saponins from the stems and leaves of P. polyphylla.
      PubDate: 2021-08-11
      DOI: 10.1007/s10337-021-04073-4
       
  • The Pharmacokinetics and Bio-distribution Studied by Simultaneous Analysis
           of Curcumin and Paclitaxel in Biosamples

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      Abstract: A simple, rapid, sensitive, robust and reproducible and specific high-performance liquid chromatography (HPLC) analysis method for the simultaneous determination of Curcumin (CU) and Paclitaxel (PTX) was developed and validated. After pretreating with citric acid/trisodium citrate (CA) buffer (pH 3.6) as stabilizer and extracting from the biosamples with ethyl acetate/methanol (90/10, v/v), CU and PTX were chromatographed on a Luna C18 column (4.6 mm × 250 mm, 5 µm) at a flow rate of 1 mL·min−1 with acetonitrile (A)/triethylamine phosphate buffer (pH 3.5; 0.012 M) (B) as the mobile phase by variable wavelength and gradient elution method of 0–9.5 (min)/55% A–45% B at 425 nm, 9.51–11.5 (min)/40% A–60% B at 227 nm, 11.51–19.0 (min)/55% A–45% B at 425 nm. The method was validated related to linearity, accuracy, precision and stability. After pretreatment, CU and PTX were stable in biological samples at room temperature for 24 h and at – 20 °C storage for 7 days. Besides, compared to CU or PTX alone, an altered pharmacokinetics in rabbits and bio-distribution behavior in rats by co-administration were observed, and its influence rules and mechanisms still need further study.
      PubDate: 2021-08-05
      DOI: 10.1007/s10337-021-04076-1
       
 
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