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  Subjects -> CHEMISTRY (Total: 925 journals)
    - ANALYTICAL CHEMISTRY (57 journals)
    - CHEMISTRY (658 journals)
    - CRYSTALLOGRAPHY (21 journals)
    - ELECTROCHEMISTRY (27 journals)
    - INORGANIC CHEMISTRY (43 journals)
    - ORGANIC CHEMISTRY (48 journals)
    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (658 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 14)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31)
ACS Applied Polymer Materials     Hybrid Journal  
ACS Catalysis     Hybrid Journal   (Followers: 54)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 22)
ACS Combinatorial Science     Hybrid Journal   (Followers: 21)
ACS Macro Letters     Hybrid Journal   (Followers: 29)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 46)
ACS Nano     Hybrid Journal   (Followers: 364)
ACS Photonics     Hybrid Journal   (Followers: 15)
ACS Symposium Series     Full-text available via subscription   (Followers: 1)
ACS Synthetic Biology     Hybrid Journal   (Followers: 24)
Acta Chemica Iasi     Open Access   (Followers: 6)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 7)
Advanced Functional Materials     Hybrid Journal   (Followers: 63)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 85)
Advances in Chemistry     Open Access   (Followers: 28)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Environmental Chemistry     Open Access   (Followers: 8)
Advances in Enzyme Research     Open Access   (Followers: 11)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 28)
Advances in Nanoparticles     Open Access   (Followers: 18)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Polymer Science     Hybrid Journal   (Followers: 49)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 13)
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: 8)
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)
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: 22)
American Journal of Chemistry     Open Access   (Followers: 34)
American Journal of Plant Physiology     Open Access   (Followers: 13)
American Mineralogist     Hybrid Journal   (Followers: 15)
Anadolu University Journal of Science and Technology A : Applied Sciences and Engineering     Open Access  
Analyst     Full-text available via subscription   (Followers: 37)
Angewandte Chemie     Hybrid Journal   (Followers: 192)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 282)
Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia     Open Access   (Followers: 1)
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 4)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 8)
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: 15)
Antiviral Chemistry and Chemotherapy     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 26)
Applied Surface Science     Hybrid Journal   (Followers: 33)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access   (Followers: 2)
Atomization and Sprays     Full-text available via subscription   (Followers: 5)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 4)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 396)
Biochemistry Insights     Open Access   (Followers: 7)
Biochemistry Research International     Open Access   (Followers: 7)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 2)
Biomacromolecules     Hybrid Journal   (Followers: 25)
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: 6)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 180)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 92)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 17)
Biosensors     Open Access   (Followers: 2)
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: 25)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
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: 12)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Carbohydrate Research     Hybrid Journal   (Followers: 24)
Carbon     Hybrid Journal   (Followers: 72)
Catalysis for Sustainable Energy     Open Access   (Followers: 10)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 10)
Catalysis Science and Technology     Hybrid Journal   (Followers: 10)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 14)
Cellulose     Hybrid Journal   (Followers: 14)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 2)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 23)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 74)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Physics Letters : X     Open Access   (Followers: 2)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 23)
Chemical Reviews     Hybrid Journal   (Followers: 228)
Chemical Science     Open Access   (Followers: 32)
Chemical Technology     Open Access   (Followers: 46)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 21)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry     Open Access  
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry & Industry     Full-text available via subscription   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 188)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 21)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Heterocyclic Compounds     Hybrid Journal   (Followers: 4)
Chemistry of Materials     Hybrid Journal   (Followers: 282)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 10)
Chemistry World     Full-text available via subscription   (Followers: 21)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 12)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 12)
Chromatographia     Hybrid Journal   (Followers: 22)
Chromatography     Open Access   (Followers: 3)
Chromatography Research International     Open Access   (Followers: 5)
Clay Minerals     Hybrid Journal   (Followers: 10)
Cogent Chemistry     Open Access   (Followers: 2)
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
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)
Communications Chemistry     Open Access   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 8)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 13)
Computational Chemistry     Open Access   (Followers: 3)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 4)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 7)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 8)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal   (Followers: 2)
Current Metabolomics     Hybrid Journal   (Followers: 6)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 10)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 13)
Current Research in Chemistry     Open Access   (Followers: 9)

        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  [2425 journals]
  • Łukasz Komsta, Yvan Vander Heyden and Joseph Sherma (Eds):
           Chemometrics in Chromatography
    • PubDate: 2019-11-01
       
  • Vipul Gupta, Pavel Nesterenko and Brett Paul: 3D Printing in Chemical
           Sciences—Applications Across Chemistry
    • PubDate: 2019-11-01
       
  • Simultaneous Determination of Various Phosphates in Water-Soluble Ammonium
           Polyphosphate
    • Abstract: Based on ion chromatography, this study developed a rapid method for simultaneous determination of linear polyphosphates (PPs) of orthophosphate (P1), pyrophosphate (P2), trimetaphosphate (P3m), tripolyphosphate (P3), tetraphosphate (P4), pentaphosphate (P5), and hexaphosphate (P6) in water-soluble ammonium polyphosphate (WAPP). Investigation indicated that the retention of PPs in column was endothermic and cooling column benefited the elution of PPs. With adjusting the elution mode, eluent (KOH) concentration, gradient time, flowrate, and column temperature, the optimized results were as follows: the injection volume of sample was 1.3 μL, column temperature was 30 °C, and flowrate of the eluent was 1.2 ml min−1. The linear equations for six phosphates are: y = 0.011cP1 + 0.021 (r = 0.9998), y = 0.012cP2 + 0.023, y = 0.011cP3m − 0.013 (r = 0.9997), y = 0.12cP3 + 0.017 (r = 0.9999), y = 0.011cP4 + 0.004 (r = 0.9983), y = 0.011cP5 − 0.082 (r = 0.9962), and y = 0.013cP6 − 0.029 (r = 0.9989), respectively. The determination ranges are: 1–500 mg L−1 for P1, P2, P3m, and P3; and 1–100 mg L−1 for P4, P5, and P6. The recovery is in the range 95–104% for P1, P2, P3m, P3, P4, P5, and P6; the detection limit is in the range 0.17–0.54 mg L−1 and RSDs of intra- and inter-day determination are 0.56–2.51% (n = 5) for seven PPs, and the analysis period is 15 min. The method was consistent with both gravimetric method and molybdenum blue method, while the RSD was in the range 0.61–1.87%. This rapid method can be applied in the determination of total phosphorus and various phosphates in PPs.
      PubDate: 2019-11-01
       
  • Multivariate Development and Optimization of Stability Indicating Method
           for Determination of Daclatasvir in Presence of Potential Degradation
           Products
    • Abstract: A specific, robust, and rapid UV-HPLC method was developed for the assay of daclatasvir (DCV) in pharmaceutical formulation in the presence of potential degradation products using quality-by-design approach. The impurity profile of DCV was studied via forced degradation procedures with subsequent characterization of the resultant degradation products using LC–MS. Central composite design with response surface methodology was utilized to simultaneously optimize four chromatographic factors: pH, elution temperature, flow rate, and organic modifier %. The first order, interaction, and quadratic effects of those four factors were evaluated for 16 responses of eight peaks “resolution (7), number of theoretical plates (8), run time (1)”. Optimum separation was achieved using Eclipse plus RP C18 column, mobile phase consisting of methanol: 0.025 M phosphate buffer pH 7.0 (58: 42 v/v), flow rate of 1.5 mL min−1at 40 °C, and detection at 303 nm. The optimized method was validated according to ICH guidelines and applied to determine DCV in pharmaceutical formulation. DCV response was linear (r = 0.9999) in the range 1.5–90 µg mL−1; inter-day and intra-day precisions were 0.28% and 0.25%, respectively, and independent t test indicated non-significant difference between inter- and intra-day means; accuracy was 100.49 ± 0.92%.
      PubDate: 2019-11-01
       
  • Is Inverse Gas Chromatography (IGC) a Convenient Method to Determine
           Compatibility of Rubber Materials'
    • Abstract: Compatibility is a key factor in formulation of polymeric compounds. Having sufficient data about solubility of components may help to create novel engineered materials. Solubility parameter has been used as a tool for predicting the compatibility of materials. In this study, the solubility parameter of natural rubber and styrene–butadiene rubber is determined through inverse gas chromatography. The 3D solubility parameter sphere for each rubber has been depicted using three components of the Hansen solubility parameter. In addition, the reliability of the procedure has been confirmed through scanning electron microscope (SEM) micrographs and Fourier-transform infrared spectroscopy (FTIR-ATR) spectra of samples. Results demonstrate NR and SBR solubility parameters to be 23.58 and 21.98 (J/cm3)0.5 at room temperature. Also, this study aimed to verify if the inverse gas chromatography method is a reliable method to be used in polymer industries as a prediction tool before compounding. Finally, results confirmed that inverse gas chromatography is a promising method in the field of rubbers. Graphic abstract
      PubDate: 2019-11-01
       
  • Simultaneous Determination of 16 Phthalate Esters in Suet Oil by GC–EIMS
           Coupled with Refrigerant Centrifugation and Ethylenediamine- N
           -propylsilane Depuration
    • Abstract: Phthalic acid esters (PAEs) are endocrine-disrupting chemicals that can enter the human body easily via contaminated food and pharmaceutical excipients. The main challenge in the detection of PAEs in oily samples is not the choice of chromatography–mass spectrometry technology but the pretreatment method. Suet oil (SO), a fatty oil obtained from Capra hircus Linnaeus or Ovis aries Linnaeus, is widely used in food additives and the processing of Chinese medicine. In this paper, refrigerant centrifugation (RC) was optimized to pretreat SO samples for the separation of PAEs and fatty acids. Extraction with acetonitrile (n-hexane saturated) combined with RC (− 15 °C, 5000 rpm, 15 min, twice) was systematically assessed by four factors (temperature, time, speed, and frequency) according to response surface methodology. Gas chromatography–electron ionization quadrupole mass spectrometry (GC–EIMS) was used as an external standard method for quantification. The correlation coefficients of 16 PAEs were all 0.999 and the lowest quantified level was 0.1 mg kg−1. The recoveries of the 16 PAEs were 82.9–105.5% with relative standard deviations of 1.5–8.5% (n = 6). Compared with solid-phase extraction (SPE), RC had higher recovery rate, lower consumption (economy ratio 65.7%), and powerful sample processing ability. Results showed that the contents of di-n-butyl phthalate (DBP) in two batches of SO were higher than the official limit published by the Ministry of Public Health of China (0.3 mg kg−1). This study provides an alternative method for the determination of PAEs in SO and other edible or medicinal animal oil with wide practicability and less matrix interference.
      PubDate: 2019-11-01
       
  • Validation and Application of Molecularly Imprinted Polymers for
           SPE/UPLC–MS/MS Detection of Gemifloxacin Mesylate
    • Abstract: Eight molecularly imprinted polymers (MIPs) were synthesized for the determination of the antibacterial agent gemifloxacin mesylate (GFM). The polymers were prepared using GFM as a template, methacrylic acid (MAA) or 4-vinylpyridine (4-VP) as functional monomers, ethylene glycol dimethacrylate (EGDMA) as a cross linker, 2,2′-azobisisobutyronitrile (AIBN) as an initiator and a mixture of dimethylsulfoxide (DMSO)/acetonitrile (ACN) (1:1, v/v) as a porogen. The optimized polymer was utilized as a solid-phase extraction (SPE) sorbent material for GFM from different matrices. Different loading, washing and elution protocols were investigated. Quantitative analysis of the extracts was performed using a newly developed ultra-performance liquid chromatography–mass spectrometry (UPLC–MS/MS) method on an Acquity BEH C18 column (100 mm × 2.1 mm, particle size of 1.7 µm). The isocratic mobile phase was a mixture of methanol (MeOH)/water (H2O) with 0.1% formic acid (70:30, v/v), the flow rate was 0.3 mL min−1 and the column temperature was 40 °C. Lomefloxacin (LOM) was used as an internal standard. The developed method was validated based on the recommendations of the International Conference on Harmonization (ICH) and was found suitable for the extraction of GFM from a pharmaceutical drug preparation and spiked human urine samples. Recovery % values ranged from 90.24 to 112.8% with relative standard deviation (RSD) of less than 7%. Graphic
      PubDate: 2019-11-01
       
  • Development and Validation of a New HPLC Method for Quantification of a
           Novel Antifungal Drug Based on 1,3,4-Thiadiazole and its Impurities
    • Abstract: Chromatographic behavior of a new antifungal drug, (2-[(Z)-1-(3,5-diphenyl-1,3,4-thiadiazol-2(3H)-ylidene)-methyl]-3,5-diphenyl-1,3,4-thiadiazol-3-ium chloride (TDZ), and its impurities was studied using several types of columns, mobile phases and elution modes. A new reversed phase high-performance liquid chromatography (HPLC) method for the determination of TDZ and its impurities in a pharmaceutical substance and dosage form (tablets, 60 mg) was developed and validated. The optimal chromatographic separation of TDZ and its impurities was performed on a 5-μm C8 column (4.6 mm × 250 mm, I.D.). The mobile phase consisted of 0.03% TFA in water (pH 2.5) and acetonitrile under gradient elution condition (from 40:80 v/v to 80:20 v/v for 20 min) at a flow rate of 1.0 mL min−1. UV detection was set at a wavelength of 250 nm. The limit of detection (LOD) and quantification (LOQ) were 0.05 and 0.1 μg mL−1, respectively. The method showed good linearity (r2 > 0.999) over the assayed concentration range (0.1–1.4 μg mL−1 for quantification of impurities and 0.005–0.013 mg mL−1 for quantification TDZ) and demonstrated good intra- and inter-day precision and accuracy. The method was validated and successfully applied for quantitative determination of TDZ and its impurities in both the pharmaceutical substance and tablets.
      PubDate: 2019-11-01
       
  • Simultaneous Determination of Caffeine, Taurine and Five Water-Soluble
           Vitamins in Tobacco Products by HPLC–MS/MS
    • Abstract: The simultaneous determination of caffeine, taurine and five water-soluble vitamins (B1, B2, B3, B9, and B12) in tobacco products by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was established in this work. Tobacco powders of sampled tobacco products were extracted with water and then filtered. The filtrates were separated on an Agilent Eclipse XDB-C18 (2.1 mm i.d × 150 mm, 3.5 μm) column using methanol: ammonium acetate aqueous solution (10 mM) as the mobile phase at a flow rate of 0.3 mL min−1 using the gradient elution mode. These analytes were detected by electrospray ionization–tandem mass spectrometry (ESI–MS/MS) using a multiple reaction monitoring method. Under the optimized conditions, the separation of caffeine, taurine and five water soluble vitamins was achieved within 12 min. The linear ranges of caffeine, taurine and vitamins B1, B2, B3, B9, and B12 were 2.000–100.0, 0.3316–3316, 0.1248–249.6, 1.600–160.0, 0.5990–29.95, 0.3150–31.50, and 0.2246–2246 μg L−1, respectively, with linear correlation coefficient greater than 0.997. The detection limits (S/N = 3) of caffeine, taurine and vitamins B1, B2, B3, B9, and B12 were 0.445, 0.079, 0.031, 0.400, 0.179, 0.079, and 0.066 μg L−1, respectively. The precisions for intra-day (n = 11) and inter-day (n = 5) were 0.09–2.23% and 0.11–2.52%, respectively. The recoveries of these seven analytes in the spiked tobacco product samples were in the range of 95.1–102.8%. The proposed method has the merits of easy operation, fast analysis, high sensitivity and accuracy, which is applicable for batch determination and surveillance on caffeine, taurine and water-soluble vitamins in commercial tobacco products.
      PubDate: 2019-11-01
       
  • Optimization of Electrospray Ionization for Liquid Chromatography
           Time-of-Flight Mass Spectrometry Analysis of Preservatives in Wood
           Leachate Matrix
    • Abstract: Triazoles and 3-iodo-2-propynyl butylcarbamate (IPBC) are commonly used wood preservatives active against a wide range of fungi and bacteria. As they are prone to leaching, their amounts need to be monitored by the industry to determine preservative loss from the products and for environmental impact assessment. Therefore, a liquid chromatography–electrospray–time-of-flight mass spectrometry (LC–ESI–TOFMS) method was developed and optimized for simultaneous quantification of triazoles and IPBC in aqueous wood extracts, specifically wood leachate. Analyte pre-concentration on a solid-phase extraction cartridge prior to the analysis yielded > 94% recoveries. ESI method parameters (e.g., solvent system, electrolyte type, electrolyte concentration, capillary and fragmentor voltages) were selected based on an initial screening followed by an in-depth optimization via design of experiments. The optimal conditions employed an acetonitrile-water solvent system with 1.7 mM ammonium acetate, capillary voltage of 4350 V, and fragmentor voltage of 115 V. The developed method was applied to industrial wood leachate samples and the matrix-affected limits of detection were found to be 1.2–1.5 µg L−1 with interlay repeatability being < 7%. Graphic
      PubDate: 2019-11-01
       
  • Determination and Chemical Profiling of Toxic Pyrrolizidine Alkaloids in
           Botanical Samples with UPLC–Q-TOFMS
    • Abstract: Pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs) can cause liver toxicity and genotoxicity in humans and animals, necessitating the development of screening tools for these alkaloids. Ultra-performance liquid chromatography–electrospray ionization-quadrupole-time-of-flight mass spectrometry (UPLC–ESI–Q-TOFMS) can provide accurate precursor and fragment ion mass information (MSE mode) as well as simultaneous quantification. A method for rapidly and accurately determining nine PAs with UPLC–ESI–Q-TOF MS was developed and validated herein. Analytes were separated using a C18 column with water containing 0.1% formic acid and acetonitrile, showing high-resolution peaks within 11 min. The validation results showed excellent linearity (R2 > 0.9951), limits of detection (0.4–2.0 ng mL−1), and limits of quantification (0.6–6.0 ng mL−1). Moreover, 70 PAs, their N-oxides precursors, and characteristic fragment ions that were generated according to their chemical structure were characterized. A method for the chemical profiling of alkaloids was also proposed using the mass information obtained from the chromatograms of the tested sample. Lycopsamine, senecionine, senkirkine, and echimidine were identified in four potentially PA-containing plants and quantified by matching with authentic standards. Eight PAs and PANOs were also tentatively identified using the mass data from the previously listed alkaloids. This approach will provide a database that can be used to instantly identify alkaloids in botanical samples.
      PubDate: 2019-11-01
       
  • Amphiphilic Star-Shaped Calix[4]resorcinarene as Stationary Phase for
           Capillary Gas Chromatography
    • Abstract: This work describes the separation performance of the amphiphilic star-shaped calix[4]resorcinarene (C4A-CL) as the stationary phase for capillary gas chromatography (GC). The statically coated C4A-CL capillary column exhibited medium polarity and high column efficiency of 3877 plates m−1 determined by naphthalene at 120 °C. Importantly, the C4A-CL column exhibited extremely high resolving capability for aliphatic analytes with varying polarity, including n-alkanes, esters, ketones, alcohols, and bromoalkanes. In addition, the C4A-CL column exhibited high selectivity and resolving capability for positional, structural and cis-/trans-isomers. Among them, the C4A-CL column displayed advantageous resolving capability over the commercial DB-17 column for aromatic amine isomers. Moreover, it was applied for the determination of isomer impurities in real samples, showing good potential in GC applications.
      PubDate: 2019-11-01
       
  • Ultrasonic Nebulization-Dispersive Solid-Phase-Monolithic Microcolumn
           Extraction Coupled with HPLC–MS/MS for Analyzing Sex Steroids in Lotion
           Samples
    • Abstract: An ultrasonic nebulization-dispersive solid-phase-monolithic microcolumn extraction method coupled with high-performance liquid chromatography–mass spectrometry was developed and applied for the extraction and analysis of 15 sex steroids in lotion samples. In this method, the analytes were microextracted from a liquid phase to a dispersive solid phase, and then, a monolithic microcolumn was prepared with these dispersive solid-phase particles using our device. In this way, a more efficient extraction method was developed. Several experimental parameters, including the extraction sorbent, amount of the adsorbent, extraction time, and extraction temperature, were optimized. Calibration curves for steroid concentrations ranging from 0.11 to 1461.00 ng mL−1 were obtained for analyzing the sex steroids. The recoveries in the determination of the sex steroids were between 53.19 and 96.99%, and the relative standard deviations ranged from 2.58 to 7.52%. These results indicated that the proposed method is a fast, sensitive, low-cost, and highly efficient extraction and enrichment technique for the analysis of nonvolatile analytes in liquid samples. Graphic
      PubDate: 2019-11-01
       
  • Determination of Three Carotenoids in Microalgae by Matrix Solid-Phase
           Dispersion Extraction and High-Performance Liquid Chromatography
    • Abstract: A HPLC method based on matrix solid-phase dispersion (MSPD) was developed for simultaneous determination of fucoxanthin, lutein and astaxanthin in different microalgae. First, the powder of microalgae was blended with C8 adsorbent. Then the SPE column made from the microalgal matrix/sorbent (1:2) was eluted with 4 mL methanol (containing 0.1% BHT). The eluent was analyzed by HPLC. A C8 column and acetonitrile (ACN)/H2O as the mobile phase were used. The coefficient (R2) of each calibration curve was higher than 0.998. Limits of detection (LODs) and limits of quantification (LOQs) for each carotenoid were 0.30 µg g−1 and 1.00 µg g−1, respectively. The recovery at three concentration levels ranged from 69.1 to 106.5%, and the RSDs were lower than 5%. As a new sample preparation method for microalgal analysis, the MSPD procedure was optimized, validated and compared with conventional methods including ultrasonic and ice-bath extraction. The MSPD–HPLC method was accurate and reproducible. It was suitable for the quantitative determination of carotenoids in microalgae.
      PubDate: 2019-11-01
       
  • Synthesis and Characterization of Fluorocarbon from Rice Husk and its
           Application as an Efficient Sorbent for Micro-Solid-Phase Extraction of N
           -Nitrosamines in Desalinated Water Samples
    • Abstract: Fluorocarbon derived from rice husk was synthesized and utilized as an efficient sorbent for micro-solid-phase extraction to determine N-nitrosamines in desalinated water samples. Three different sorbents from pure rice husk (rice husk ash, sulfonated rice husk, and fluorocarbon) were synthesized. Various techniques were used to characterize the physicochemical properties of the sorbents. N-Nitrosamine mixtures (N-nitrosodimethylamine, N-nitrosodi-n-propylamine, and N-nitrosodiphenylamine) were used as target analytes for micro-solid-phase extraction. The factors influencing the performance of micro-solid-phase extraction, such as the selection of suitable sorbent, desorption solvent, desorption time, sample pH, and extraction time, were optimized. Under the optimized conditions, the newly improved micro-solid-phase extraction method provided a linear range between 1.0 and 50 µg/L with R2 value ranges from 0.9916 to 0.9998. The limit of quantification ranges between 0.01 and 0.004 µg/L with satisfactory intraday and interday precision ranging from 3.9 to 5.1% and 4.7 to 7.5%, respectively. Recovery experiments evaluated the accuracy of the micro-solid-phase extraction; the recoveries were in the range of 85.6–102.4%. The micro-solid-phase extraction method was successfully utilized for the sensitive, accurate, and precise trace-level detection of N-nitrosamines in desalinated water samples with satisfactory results.
      PubDate: 2019-10-16
       
  • Margareta Séquin: The Chemistry of Plants and Insects: Plants, Bugs
           and Molecules
    • PubDate: 2019-10-01
       
  • Michele Suman (Ed): Food Contact Materials Analysis: Mass Spectrometry
           Techniques
    • PubDate: 2019-10-01
       
  • Synthesis of Octyl-Quaternary Ammonium Mixed-Mode Stationary Phase by
           Vapor Deposition Approach and Its Application in Compound Preparation
           Separation
    • Abstract: An octyl-quaternary ammonium (Sil-C8-QA)-modified silica stationary phase was prepared by a two-step vapor deposition method which can substantially reduce the consumption of toxic organic solvents. The structure of the dual-functional ligands stationary phase was characterized by Fourier transform infrared spectroscopy and solid-state 13C CP/MAS NMR. Following elemental analysis, the surface density of octyl and quaternary ammonium bonding amount is 2.13 µmol m−2 and 0.77 µmol m−2, respectively. The efficiency and selectivity of the two-ligand phases were compared with two sole functional ligand phases: quaternary ammonium (Sil-QA)- and octyl-modified silica (Sil-C8). Chromatographic evaluation demonstrated a mixed-mode reversed-phase/anion-exchange retention property on the Sil-C8-QA column. The retention behavior of a homologous series of alkylbenzoic acids on the synthesized phase was systematically studied by changing the pH, ionic, and solvent strength of the mobile phase. A well-established mixed-model mechanism was confirmed. The Sil-C8-QA phase can predominantly enhance the retention of acidic drugs and improve their selectivity. It was also successfully applied to the simultaneous separation and determination of three kinds of compound preparations with large differences in component polarity. Graphic abstract
      PubDate: 2019-10-01
       
  • Congress, Conferences, and Workshops
    • PubDate: 2019-09-26
       
  • Congress, Conferences, and Workshops
    • PubDate: 2019-09-03
       
 
 
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