Subjects -> CHEMISTRY (Total: 1021 journals)
    - ANALYTICAL CHEMISTRY (59 journals)
    - CHEMISTRY (746 journals)
    - CRYSTALLOGRAPHY (23 journals)
    - ELECTROCHEMISTRY (28 journals)
    - INORGANIC CHEMISTRY (45 journals)
    - ORGANIC CHEMISTRY (49 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (746 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: 14)
ACS Catalysis     Hybrid Journal   (Followers: 76)
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: 3)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 49)
ACS Nano     Hybrid Journal   (Followers: 448)
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: 26)
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: 53)
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: 234)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 352)
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: 483)
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: 213)
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: 25)
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: 265)
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: 224)
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: 336)
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: 24)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)

        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  [2658 journals]
  • 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
       
  • Impurity Profiling of Novel Oxazolidinone Antibacterial Agent: WCK 4086

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      Abstract: WCK 4086 is new antibacterial drug being developed to treat infections caused by Gram positive bacteria. This study describes development of mass spectrometry (MS) compatible reversed phase liquid chromatographic method for separation, identification and quantification of the related compounds in WCK 4086. Four process related compounds and seven degradation products (DPs) were separated and structurally identified with the use of liquid chromatography tandem mass spectrometry. Three process-related compounds were synthesized and characterized using MS and nuclear magnetic resonance spectrometry. Acid/base hydrolysis produced three DPs and oxidation produced four DPs. Method validation activity was performed to increase the acceptability of the developed method. The method was precise and accurate; accuracy exceeded 97.04% with a precision of less than 5.55%. The impurities could be detected as low as 0.05 µg mL−1. The methodology was used for the batch release and stability studies of the WCK 4086 used in the preclinical studies.
      PubDate: 2021-09-30
       
  • Congress, Conferences, and Workshops

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      PubDate: 2021-09-29
       
  • Determination of 1,3-Butadiene Migrated from Butadiene-Based Polymers to
           Air and Water Using Sorbent Tubes and Purge-and-Trap

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      Abstract: Background and objective 1,3-Butadiene has wide industrial application with main focus on production of butadiene-based polymers. The accurate determination of 1,3-butadiene is complicated by its high volatility. The aim of this study was to develop the method for determination of 1,3-butadiene migrated from butadiene-based polymers to air and water based on thermal desorption–gas chromatography–mass spectrometry. Methods Purge-and-trap method was used for transferring analyte from water to gas phase followed by trapping on multi-bed sorbent tube (Carbopack B+X). Conclusions The calibration plots for air and water with coefficients of determination R 2 > 0.99 were obtained in ranges 2–20, 10–200 and 50–1000 ng. The limits of detection and quantification of 1,3-butadiene were 0.02 ng and 0.06 ng, respectively. The accuracy of the developed method expressed in spike recoveries was in the range from 92 to 101% for air, and from 94 to 95% for water, with relative standard deviations below 10% for both matrices. The developed method was successfully applied for determination of 1,3-butadiene migration level from personal protective equipment (shoes) to air and water. The concentrations of 1,3-butadiene migrated to water and air were 0.044 µg L−1 and 0.91 µg m−3, respectively. Graphic
      PubDate: 2021-09-25
       
  • Determination of Hydrocarbons in n-Butane on Porous Layer Capillary
           Columns with Nonpolar Stationary Phase

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      Abstract: A comparative assessment is performed of the separation capability of three types of PLOT capillary columns: PTMSP032 (poly(1-trimethylsilyl-1-propyne)), Rt-Q-BOND (polydivinylbenzene), GS-GasPro (silica), and it is studied of the possibility of their use for the determination of impurities in commercial (target, technical) n-butane. Satisfactory separation of alkanes, alkenes, arenes and methanol was achieved on PTMSP032 and Rt-Q-BOND columns. The effect of the main component amount of the mixture on the separation of trace amounts of hydrocarbons and methanol is studied. It is shown that the macrozone (> 99%) of n-butane is selectively separated from the accompanying impurities. With an increase in the injected sample volume, the resolution for the peaks of C1–C2 hydrocarbons and the structural isomers of o-, m-, and p-xylenes on the PTMSP032 column is significantly higher than on the Rt-Q-BOND column. A comparative assessment of the precision of the measurements of the hydrocarbons and methanol retention times on PTMSP032 and Rt-Q-BOND is characterized by a relative standard deviation (RSD) of not more than 0.3%.
      PubDate: 2021-09-21
       
  • 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
       
  • 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
       
  • 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 of a Novel and Stability Indicating RP-HPLC-UV Method for
           Simultaneous Analysis of Carbetocin and Ten Impurities in Carbetocin
           Injection Products

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      Abstract: A novel, simple and stability indicating reverse-phase high performance liquid chromatographic method with UV detection at 220 nm (RP-HPLC-UV) was established to realize the simultaneous analysis of carbetocin and ten related impurities. This paper performed the most comprehensive impurity profiling of carbetocin, including the synthesis-related impurities, the isomers of carbetocin and the degradants formed from the forced degradation research, the structures of which were tentatively identified by a two-dimensional liquid chromatography-mass spectrometry technology. The novelty of this RP-HPLC-UV method was demonstrated by its satisfactory resolution and selectivity, which was achieved using an YMC-pack C18 column kept at 40 ℃, and optimal organic modifier gradient. The mobile phase A was potassium dihydrogen phosphate buffer (pH 6.5)—acetonitrile (80:20, v/v), and the mobile phase B was potassium dihydrogen phosphate buffer (pH 6.5)—acetonitrile (72:28, v/v). The forced degradation research proved the stability-indicating capacity of the method and validation study was performed according to ICH requirements. In summary, this RP-HPLC-UV method could support the simultaneous determination of related substances of carbetocin in bulk drug and in pharmaceutical formulations.
      PubDate: 2021-08-28
      DOI: 10.1007/s10337-021-04083-2
       
  • 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
       
  • Development of a Novel HPLC Method for the Analysis of Impurities in
           Meropenem and Identification of Unknown Impurities by 2D LC-IT-TOF MS

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      Abstract: A novel stability-indicating HPLC method for the quantitative determination of impurities in meropenem raw material was established and fully validated for the further improvement of the official monograph in Pharmacopeia. The method was carried out on a Shim-Pack CLC-ODS column with UV detection at 220 nm. The influences of different band columns, composition ratio of mobile phase, gradient elution procedure, and pH value of mobile phase on separation of impurities in meropenem were investigated. The parameters specificity, precision, linearity, range, accuracy, limit of detection, limit of quantitation, and robustness were studied according to the regulatory guidelines recommended by the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). The linear regression analysis results of EP impurity A and EP impurity B show that there is a good linear relationship between response and concentration, and the correlation coefficients are 0.9999 and 1.0000, respectively. The accuracy of EP impurity A and EP impurity B is between 90 and 104%. Through analysis, the LOD and LOQ values of EP impurities A and B were measured and found to be 0.22 and 0.74 µg mL-1, respectively. Moreover, three unknown degradation impurities in meropenem were identified by two-dimensional liquid chromatography tandem with high-resolution ion trap/time-of-flight mass spectrometry in electrospray ionization mode. Compared with the current method in Pharmacopeia, the developed method had greatly improved the separation and detection ability of impurities. The established method was highly specific, sensitive, and accurate for reliable routine quality control of meropenem raw material. The structures of unknown impurities were characterized based on the MS/MS data.
      PubDate: 2021-08-22
      DOI: 10.1007/s10337-021-04081-4
       
  • Impurity Profiling of Baclofen Using Gradient HPLC–UV Method

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      Abstract: The GABAB receptor agonist baclofen is a medication commonly used for the treatment of muscle spasticity. It is an amino acid and related to the neurotransmitter GABA. In this study, we developed a new, gradient high-performance liquid chromatography (HPLC) method for the impurity assessment of baclofen, which is appropriate for pharmacopoeial purposes. Since the impurities related to the synthesis pathway are acids, zwitterionic, or neutral, the method development is challenging. However, the separation of all components was achieved on a C18 stationary phase using a water–acetonitrile–trifluoroacetic acid gradient. A limit of detection (LOD) of at least 0.02% was registered for all specified impurities. Additionally, CAD detection was performed to detect potential impurities lacking off a chromophore. The baclofen batches analyzed are far more pure than expected. All impurities were found below the specification limit, and thus, they can be regarded as unspecified. Moreover, the required runtime could be significantly reduced compared to the current USP or Ph. Eur. method.
      PubDate: 2021-08-13
      DOI: 10.1007/s10337-021-04079-y
       
  • 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
       
  • Investigation to Identify the Root Cause of Out-of-Specification Results
           for Color of a Topical Pour-on Drug Product: A Case Study

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      Abstract: One topical pour-on drug product formed a slightly yellow color and continued to increase the intensity over the shelf life of the product. This caused out-of-specification (OOS) results for the color of the drug product. Based on the experimental results obtained using high-performance liquid chromatography, high-resolution mass spectrometry, and a color measurement spectrophotometer, the root cause of color formation in the OOS sample was identified and confirmed to be 3,3′,5,5′-tetra-t-butyl-4,4’-stilbenequinone (2BHT-QM), an oxidative degradation product of t-butylated hydroxytoluene (BHT) which is used in this drug product as an antioxidant. The content of 2BHT-QM in the OOS sample was estimated to be about 0.9–1 ppm by two independent analytical methods. The results from our investigation clearly indicated that BHT can cause color change in liquid or semi-liquid formulation (drug product) and we report this for the first time. The investigation approach and rationale of described in this paper should be helpful for similar investigations when BHT is used in liquid or semi-liquid formulations.
      PubDate: 2021-08-09
      DOI: 10.1007/s10337-021-04077-0
       
  • 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
       
  • Characterization of Surface Properties and Hydrocarbon Adsorption of
           Torrefied Cardboard via Inverse Gas Chromatography and Complementary
           Analytical Techniques

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      Abstract: Inverse gas chromatography (IGC), atomic absorption spectroscopy (AAS), and Fourier-transform infrared spectroscopy (FTIR) were employed to investigate the surface properties of torrefied cardboard samples and their hydrocarbon adsorption. Three torrefied cardboard samples, TC-200, TC-250, and TC-300, were prepared at 200, 250, and 300 °C, respectively. A series of n-alkanes, BTX (benzene, toluene, and p-xylene), and several polar probes (dichloromethane, acetone, ethyl acetate, and tetrahydrofuran) were selected as molecular probes to measure the molar adsorption enthalpies ( \({\Delta H}_{\mathrm{m}}\) ), dispersive surface energies, and acid–base properties of torrefied cardboard samples. The \({\Delta H}_{\mathrm{m}}\) values of hydrocarbons measured on TC-300 and TC-250 were more exothermic than those measured for TC-200 by about 19 and 13%, respectively. The \({\Delta H}_{m}\) values of benzene, toluene, and p-xylene on three torrefied cardboard samples became more negative than those of n-hexane, n-heptane, and n-octane by approximately 17–20%. Surface free energy analysis using molecular probes found that TC-300 exhibited higher dispersive and specific surface energy than TC-250 and TC-200 did. From FTIR spectra and elemental analysis via AAS, C=C moieties in the carbonaceous substances and inorganic mineral compositions are responsible for enhanced dispersive and specific surface energy of TC-300. BTX adsorption isotherms on torrefied cardboard samples were well-fitted using the Freundlich model. Fitted parameters of adsorption isotherms also found that TC-300 had a larger adsorption capacity toward BTX than TC-250, TC-200, and non-torrefied cardboard did.
      PubDate: 2021-08-04
      DOI: 10.1007/s10337-021-04071-6
       
 
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