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Journal Cover Journal of Chromatography A
  [SJR: 1.774]   [H-I: 184]   [116 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0021-9673
   Published by Elsevier Homepage  [3048 journals]
  • Polyamide/titania hollow nanofibers prepared by core–shell
           electrospinning as a microextractive phase in a fabricated sandwiched
           format microfluidic device
    • Authors: Omid Rezvani; Mahin Hashemi Hedeshi; Habib Bagheri
      Pages: 1 - 9
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Omid Rezvani, Mahin Hashemi Hedeshi, Habib Bagheri
      In this study, a low–cost microfluidic device from polymethyl methacrylate was fabricated by laser engraving technique. The device is consisted of a central chip unit with an aligned microchannel. Both sides of the engraved microchannel were sandwiched by two synthesized sheets from polyamide/titania (PA/TiO2) hollow nanofibers as extractive phases. The inlet and outlet of the device were connected to the polyether ether ketone tubes, while a peristaltic pump was used to deliver both sample and desorbing solvent through the microchannel. The recorded scanning electron microscopy images from the surface of the synthesized PA/TiO2 nanofibers, exhibit a good degree of homogeneity and porosity throughout their structures. Also, the presence of titanium was indicated by the energy dispersive X-ray analysis, while the recorded Fourier transform infrared spectra confirmed their chemical structures. The addition of titania in the composition of polyamide nanofibers, not only improved the mechanical stability of the extractive phase but also enhanced its extraction capability. The major parameters associated with the extraction performance were studied and eventually the method was validated by the use of a gas chromatography–mass spectrometry. The limits of detection for the selected triazines were between 0.01 and 0.03ngmL−1, while the limits of quantification ranged from 0.04 to 0.1ngmL−1. In addition, the interday and intraday reproducibility (RSD%) were lower than 6.6% (n=3). The calibration graph for atrazine was linear in the range of 0.2–50ngmL−1 while two linear ranges for ametryn and terbutryn (0.1–10 and 20–500ngmL−1) were achieved. Relative recoveries were between 89 and 98% with the regression coefficient range of 0.9969–0.9991.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.052
      Issue No: Vol. 1528 (2017)
       
  • A dispersive liquid-liquid microextraction based on solidification of
           floating organic droplet followed by injector port silylation coupled with
           gas chromatography–tandem mass spectrometry for the determination of
           nine bisphenols in bottled carbonated beverages
    • Authors: Kapil Mandrah; G.N.V. Satyanarayana; Somendu Kumar Roy
      Pages: 10 - 17
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Kapil Mandrah, G.N.V. Satyanarayana, Somendu Kumar Roy
      In the present study, a method has been efficiently developed for the first time to determine nine bisphenol analogues [bisphenol A (BPA), bisphenol C (BPC), bisphenol AF (BPAF), bisphenol E (BPE), bisphenol F (BPF), bisphenol G (BPG), bisphenol M (BPM), bisphenol S (BPS), and bisphenol Z (BPZ)] together in bottled carbonated beverages (collected from the local market of Lucknow, India) using dispersive liquid-liquid microextraction process. This is based on solidification of floating organic droplet (DLLME-SFO) followed by injector port silylation coupled with gas chromatography–tandem mass spectrometry. The process investigated parameters of DLLME-SFO (including the type of extraction and disperser solvents with their volumes, effect of pH, ionic strength, and the sample volume), factors influencing to injection port derivatization like, collision energy, injector port temperature, derivatizing reagent with sample injection volume, and type of organic solvent. BPA, BPF, BPZ, and BPS were detected in each sample; whereas, other bisphenols were also detected in some carbonated beverage samples. After optimizing the required conditions, good linearity of analytes was achieved in the range of 0.097–100ngmL−1 with coefficients of determination (R2) ≥0.995. Intra-day and inter day precision of the method was good, with relative standard deviation (% RSD)≤10.95%. The limits of detection (LOD) and limits of quantification (LOQ) values of all bisphenols were ranged from 0.021 to 0.104ngmL−1 and 0.070 to 0.343ngmL−1, respectively. The recovery of extraction was good (73.15–95.08%) in carbonated beverage samples and good enrichment factors (96.36–117.33) were found. Thus, the developed method of microextraction was highly precise, fast, and reproducible to determine the level of contaminants in bottled carbonated beverages.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.071
      Issue No: Vol. 1528 (2017)
       
  • Fast and highly selective determination of hemagglutinin content in
           quadrivalent influenza vaccine by reversed-phase high-performance liquid
           chromatography method
    • Authors: Barry Lorbetskie; Nathalie Fortin; Laura Durno; Junzhi Wang; Changgui Li; Xuguang Li; Michel Girard; Simon Sauvé
      Pages: 18 - 24
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Barry Lorbetskie, Nathalie Fortin, Laura Durno, Junzhi Wang, Changgui Li, Xuguang Li, Michel Girard, Simon Sauvé
      Seasonal inactivated quadrivalent influenza vaccines are currently formulated to include antigens from two strains of influenza A and a strain from each of the two circulating influenza B virus lineages. However, the applicability of the potency assay currently required for the release of vaccines has been hindered due to cross-reactivity between the two B strains. In this study, a reversed-phase high-performance liquid chromatography method previously developed for the separation and quantitative determination of the hemagglutinin content in trivalent influenza vaccine preparations was further extended and found to be adaptable for the assessment of all four hemagglutinin antigens present in quadrivalent influenza vaccines. Vaccines prepared from monovalent bulks and commercial quadrivalent products from the past three vaccination seasons in the Northern Hemisphere were tested with the new method. The results showed excellent resolution of all four hemagglutinins from frequently interfering formulation agents such as surfactants. This method provides a simple approach for fast evaluation of quality and hemagglutinin strain identification in influenza vaccines. It is also the only physicochemical method capable of distinguishing the B strains in quadrivalent influenza vaccines.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.041
      Issue No: Vol. 1528 (2017)
       
  • Determination of reversed-phase high performance liquid chromatography
           based octanol-water partition coefficients for neutral and ionizable
           compounds: Methodology evaluation
    • Authors: Chao Liang; Jun-qin Qiao; Hong-zhen Lian
      Pages: 25 - 34
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Chao Liang, Jun-qin Qiao, Hong-zhen Lian
      Reversed-phase liquid chromatography (RPLC) based octanol-water partition coefficient (logP) or distribution coefficient (logD) determination methods were revisited and assessed comprehensively. Classic isocratic and some gradient RPLC methods were conducted and evaluated for neutral, weak acid and basic compounds. Different lipophilicity indexes in logP or logD determination were discussed in detail, including the retention factor logkw corresponding to neat water as mobile phase extrapolated via linear solvent strength (LSS) model from isocratic runs and calculated with software from gradient runs, the chromatographic hydrophobicity index (CHI), apparent gradient capacity factor (kg’) and gradient retention time (tg). Among the lipophilicity indexes discussed, logkw from whether isocratic or gradient elution methods best correlated with logP or logD. Therefore logkw is recommended as the preferred lipophilicity index for logP or logD determination. logkw easily calculated from methanol gradient runs might be the main candidate to replace logkw calculated from classic isocratic run as the ideal lipophilicity index. These revisited RPLC methods were not applicable for strongly ionized compounds that are hardly ion-suppressed. A previously reported imperfect ion-pair RPLC method was attempted and further explored for studying distribution coefficients (logD) of sulfonic acids that totally ionized in the mobile phase. Notably, experimental logD values of sulfonic acids were given for the first time. The IP-RPLC method provided a distinct way to explore logD values of ionized compounds.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.064
      Issue No: Vol. 1528 (2017)
       
  • Determination of γ-hydroxybutyrate in human urine samples by ion
           exclusion and ion exchange two-dimensional chromatography system
    • Authors: Junwei Liu; Zhifen Deng; Zuoyi Zhu; Yong Wang; Guoqing Wang; Yu-an Sun; Yan Zhu
      Pages: 35 - 40
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Junwei Liu, Zhifen Deng, Zuoyi Zhu, Yong Wang, Guoqing Wang, Yu-an Sun, Yan Zhu
      A two-dimensional ion chromatography system was developed for the determination of γ-hydroxybutyrate (GHB) in human urine samples. Ion exclusion chromatography was used in the first dimensional separation for elimination of urine matrices and detection of GHB above 10mgL−1, ion exchange chromatography was used in the second dimensional separation via column-switching technique for detection of GHB above 0.08mgL−1. Under the optimized chromatographic conditions, the ion exclusion and ion exchange chromatography separation system exhibited satisfactory repeatability (RSD<3.1%, n=6) and good linearity in the range of 50–1000mgL−1 and 0.5–100mgL−1, respectively. By this method, concentrations of GHB in the selected human urine samples were detected in the range of 0–1.57mgL−1. The urine sample containing 0.89mgL−1 GHB was selected to evaluate the accuracy; the spiked recoveries of GHB were 95.9-102.8%. The results showed that the two-dimensional ion chromatography system was convenient and practical for the determination of GHB in human urine samples.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.069
      Issue No: Vol. 1528 (2017)
       
  • Online extraction of antihypertensive drugs and their metabolites from
           untreated human serum samples using restricted access carbon nanotubes in
           a column switching liquid chromatography system
    • Authors: Henrique Dipe de Faria; Carolina Tosin Bueno; Jose Eduardo Krieger; Eduardo Moacyr Krieger; Alexandre Costa Pereira; Paulo Caleb Júnior Lima Santos; Eduardo Costa Figueiredo
      Pages: 41 - 52
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Henrique Dipe de Faria, Carolina Tosin Bueno, Jose Eduardo Krieger, Eduardo Moacyr Krieger, Alexandre Costa Pereira, Paulo Caleb Júnior Lima Santos, Eduardo Costa Figueiredo
      A novel analytical method was developed to determine 5 antihypertensive drugs of different pharmacological classes (angiotensin-converting enzyme inhibitors, calcium channel blockers, α-2 adrenergic receptor agonists, angiotensin II receptor blockers, and aldosterone receptor antagonists) and some of their metabolites in human serum. The untreated samples were directly analyzed in a column switching system using an extraction column packed with restricted access carbon nanotubes (RACNTs) in an ultra-high performance liquid chromatography coupled to a mass spectrometer (UHPLC–MS/MS). The RACNTs column was able to exclude approximately 100% of proteins from the samples in 2.0min, maintaining the same performance for about 300 analytical cycles. The method was validated in accordance with Food and Drug Administration (FDA) guidelines, being linear for all the determined analytes in their respective analytical ranges (coefficients of determination higher than 0.99) with limits of detection (LODs) and quantification (LOQs) ranging from 0.09 to 10.85μgL−1 and from 0.30 to 36.17μgL−1, respectively. High recovery values (88–112%) were obtained as well as suitable results for inter and intra-assay accuracy and precision. The method provided an analytical frequency of 5 samples per hour, including the sample preparation and separation/detection steps. The validated method was successfully used to analyze human serum samples of patients undergoing treatment with antihypertensive drugs, being useful for pharmacometabolomic, pharmacogenomic, and pharmacokinetic studies.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.072
      Issue No: Vol. 1528 (2017)
       
  • Simultaneous determination of three pesticide adjuvant residues in
           plant-derived agro-products using liquid chromatography-tandem mass
           spectrometry
    • Authors: Hui Li; Zejun Jiang; Xiaolin Cao; Hang Su; Hua Shao; Fen Jin; A.M. Abd El-Aty; Jing Wang
      Pages: 53 - 60
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Hui Li, Zejun Jiang, Xiaolin Cao, Hang Su, Hua Shao, Fen Jin, A.M. Abd El-Aty, Jing Wang
      Herein, an accurate and reliable isotope-labelled internal standard method was developed and validated for simultaneous determination of three polar pesticide adjuvants, namely 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone in plant-derived agro-products. Matrices, including apple, cabbage, tomato, cucumber, rice, and wheat were extracted with a modified quick, easy, cheap, effective, rugged, and safe “QuEChERS” method and purified with a new clean-up sorbent (Z-Sep). A hydrophilic interaction liquid chromatography column (HILIC), exhibiting a lipophilic-hydrophilic character, was used to separate the three analytes over 10min using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Matrix effects in various matrices were evaluated and an isotope-labelled internal standard method was employed to compensate for ion enhancement/suppression effects. At three fortification levels (2.0, 5.0, and 20.0μg/kg), the mean recoveries ranged from 78.5 to 112.1% with relative standard deviations (RSDs)<11.0% for all tested analytes. The limits of detection (LODs) and quantification (LOQs) were 0.04–0.45 and 0.12–1.58μg/kg in various matrices, respectively. The developed experimental protocol was successfully applied to monitor different samples purchased from local markets in Beijing, China. In conclusion, the developed method exhibited both high sensitivity and satisfactory accuracy and is suitable for the simultaneous determination of the three tested pesticide adjuvant residues in agro-products of plant origin.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.075
      Issue No: Vol. 1528 (2017)
       
  • Broad screening of illicit ingredients in cosmetics using
           ultra-high-performance liquid chromatography-hybrid quadrupole-Orbitrap
           mass spectrometry with customized accurate-mass database and mass spectral
           library
    • Authors: Xianshuang Meng; Hua Bai; Teng Guo; Zengyuan Niu; Qiang Ma
      Pages: 61 - 74
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Xianshuang Meng, Hua Bai, Teng Guo, Zengyuan Niu, Qiang Ma
      Comprehensive identification and quantitation of 100 multi-class regulated ingredients in cosmetics was achieved using ultra-high-performance liquid chromatography (UHPLC) coupled with hybrid quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS). A simple, efficient, and inexpensive sample pretreatment protocol was developed using ultrasound-assisted extraction (UAE), followed by dispersive solid-phase extraction (dSPE). The cosmetic samples were analyzed by UHPLC-Q-Orbitrap HRMS under synchronous full-scan MS and data-dependent MS/MS (full-scan MS1/dd-MS2) acquisition mode. The mass resolution was set to 70,000 FWHM (full width at half maximum) for full-scan MS1 and 17,500 FWHM for dd-MS2 stage with the experimentally measured mass deviations of less than 2ppm (parts per million) for quasi-molecular ions and 5ppm for characteristic fragment ions for each individual analyte. An accurate-mass database and a mass spectral library were built in house for searching the 100 target compounds. Broad screening was conducted by comparing the experimentally measured exact mass of precursor and fragment ions, retention time, isotopic pattern, and ionic ratio with the accurate-mass database and by matching the acquired MS/MS spectra against the mass spectral library. The developed methodology was evaluated and validated in terms of limits of detection (LODs), limits of quantitation (LOQs), linearity, stability, accuracy, and matrix effect. The UHPLC-Q-Orbitrap HRMS approach was applied for the analysis of 100 target illicit ingredients in 123 genuine cosmetic samples, and exhibited great potential for high-throughput, sensitive, and reliable screening of multi-class illicit compounds in cosmetics.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.11.004
      Issue No: Vol. 1528 (2017)
       
  • Explicit role of ionic strength in retention behavior of polystyrene latex
           particles in sedimentation field-flow fractionation: Slip boundary model
    • Authors: Kyunil Rah; Sujeong Han; Jaeyeong Choi; Chul Hun Eum; Seungho Lee
      Pages: 75 - 82
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Kyunil Rah, Sujeong Han, Jaeyeong Choi, Chul Hun Eum, Seungho Lee
      We investigate an explicit role of the ionic strength in the retention behaviors of polystyrene (PS) latex particles in sedimentation field-flow fractionation (SdFFF) by hinging upon the retention theory recently developed [1] as R = ( R o + v b * ) / ( 1 + v b * ) . Here R is an experimental retention ratio, and R o is the analytical expression of the standard retention theory based on the parabolic flow velocity. The reduced boundary velocity v b * is expressed in terms of the ionic strength I of the carrier liquid as v b * = v b , o * / ( 1 + ε I ) , where v b , o * = 0.070 and ε =60 mM−1 for all the PS latex systems under investigation. We then apply this to study the explicit ionic strength effect on the retention behaviors of PS beads of 200, 300, 400, and 500nm, respectively. As a primary result, the strong dependence of the retention ratio on the ionic strength can be quantitatively accounted for in an excellent accuracy: The slip effect at the channel surface is significant, particularly when I ≲0.5mM, without showing any distinguishable dependence on the specific additives to control I, such as FL-70, SDS, NaNO3, and NaN3. Based on the present study, we put forward an experimental means to estimate the ionic strength of an aqueous solution using an FFF technique.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.078
      Issue No: Vol. 1528 (2017)
       
  • Integrated microreactor for enzymatic reaction automation: An easy step
           toward the quality control of monoclonal antibodies
    • Authors: Yoann Ladner; Silvia Mas; Gaelle Coussot; Killian Bartley; Jérôme Montels; Jacques Morel; Catherine Perrin
      Pages: 83 - 90
      Abstract: Publication date: 15 December 2017
      Source:Journal of Chromatography A, Volume 1528
      Author(s): Yoann Ladner, Silvia Mas, Gaelle Coussot, Killian Bartley, Jérôme Montels, Jacques Morel, Catherine Perrin
      The main purpose of the present work is to provide a fully integrated miniaturized electrophoretic methodology in order to facilitate the quality control of monoclonal antibodies (mAbs). This methodology called D-PES, which stands for Diffusion-mediated Proteolysis combined with an Electrophoretic Separation, permits to perform subsequently mAb tryptic digestion and electrophoresis separation of proteolysis products in an automated manner. Tryptic digestion conditions were optimized regarding the influence of enzyme concentration and incubation time in order to achieve similar enzymatic digestion efficiency to that obtained with the classical methodology (off-line). Then, the optimization of electrophoretic separation conditions concerning the nature of background electrolyte (BGE), ionic strength and pH was realized. Successful and repeatable electrophoretic profiles of three mAbs digests (Trastuzumab, Infliximab and Tocilizumab), comparable to the off-line digestion profiles, were obtained demonstrating the feasibility and robustness of the proposed methodology. In summary, the use of the proposed and optimized in-line approach opens a new, fast and easy way for the quality control of mAbs.

      PubDate: 2017-11-15T20:35:24Z
      DOI: 10.1016/j.chroma.2017.10.066
      Issue No: Vol. 1528 (2017)
       
  • On-chip pulsed electromembrane extraction as a new concept for analysis of
           biological fluids in a small device
    • Authors: Monireh Karami; Yadollah Yamini; Yousef Abdossalami Asl; Maryam Rezazadeh
      Pages: 1 - 9
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Monireh Karami, Yadollah Yamini, Yousef Abdossalami Asl, Maryam Rezazadeh
      In the present work, an on-chip pulsed electromembrane extraction technique followed by HPLC-UV was developed for the analysis of codeine, naloxone and naltrexone as model analytes in biological fluids. The chip consisted of two channels for the introduction of the donor and acceptor phases. The channels were carved in two poly (methyl methacrylate) plates and a porous polypropylene membrane, which is impregnated by an organic solvent separating the two channels. Two platinum electrodes were mounted on the bottom of these channels and a pulsed electrical voltage was applied as an electrical driving force for the migration of ionized analytes from the sample solution through the porous sheet membrane into the acceptor phase. Using the pulsed voltage provided effective and reproducible extractions and could successfully overcome the disadvantages of applying constant voltages. Effective parameters of on-chip pulsed electromembrane extraction such as chemical composition of the organic solvent, applied voltage, pH of the donor and acceptor phases, flow rate and pulse duration were optimized using one-variable-at-a-time method. Under the optimized conditions, the model analytes were effectively extracted from different matrices and good linearity in the range of 10.0–500.0μgL−1 was achieved for calibration curves with coefficients of determinations (R2) higher than 0.997. Extraction recoveries and%RSDs were obtained in the ranges of 28.6–32.9% and 2.15–3.8, respectively. Also, limits of detection were obtained in the ranges of 5–10μgL−1 and 2–5μgL−1 in plasma and urine samples, respectively.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.049
      Issue No: Vol. 1527 (2017)
       
  • Multifunctionalized mesoporous silica as an efficient reversed-phase/anion
           exchange mixed-mode sorbent for solid-phase extraction of four acidic
           nonsteroidal anti-inflammatory drugs in environmental water samples
    • Authors: Yun Li; Chaonan Huang; Jiajia Yang; Junyu Peng; Jing Jin; Huilian Ma; Jiping Chen
      Pages: 10 - 17
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Yun Li, Chaonan Huang, Jiajia Yang, Junyu Peng, Jing Jin, Huilian Ma, Jiping Chen
      A mesoporous silica Santa Barbara Amorphous-15 (SBA-15) has been first functionalized with 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (a silane with three amines) and then reacted with an excess of phenyl glycidyl ether to generate a mixed-mode anion-exchanger containing both anion-exchange (three amines) and reversed-phase (multiple ether-linked phenyls) functionalities in a single branched ligand. The resulting material has been characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption measurements, Fourier-transform infrared spectroscopy, and elemental analysis. The results obtained indicated a BET specific surface area (SBET) of 362.5m2 g−1, a pore volume of 0.70cm3 g−1 with a narrow pore size distribution centered at 6.6nm, and carbon and nitrogen contents of 28.30% and 2.84%, respectively. The dimensions of these particles (∼5μm diameter, ∼60μm length), their large surface areas, their high-density functionalities and anion-exchange mixed-mode characteristics make them very attractive for highly effective solid phase extraction (SPE) of acidic nonsteroidal anti-inflammatory drugs (NSAIDs). The important parameters on extraction efficiency including sample pH, breakthrough volume, type and volume of eluent were optimized. A simple and sensitive analytical method based on mixed-mode SPE coupled to high-performance liquid chromatography with ultraviolet detection (HPLC-UV) was developed and successfully applied to the analysis of four NSAIDs (ketoprofen, naproxen, diclofenac, and ibuprofen) in spiked real water samples with satisfactory recoveries (80.6–110.9%) and repeatability (relative standard deviation <11.3%, n=3). The limit of detections of four NSAIDs were 0.006–0.070μgL−1 for tap water, and 0.014–0.16μgL−1 for river water and wastewater, with the enrichment factors of 806–1109-fold.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.051
      Issue No: Vol. 1527 (2017)
       
  • Partition constant database for totally organic biphasic systems
    • Authors: Colin F. Poole
      Pages: 18 - 32
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Colin F. Poole
      A database of partition constants for more than 300 compounds of industrial, environmental and biological interest in nineteen totally organic biphasic systems is reported. The biphasic systems consist of the polar organic solvents acetonitrile, methanol, N,N-dimethylformamide, dimethyl sulfoxide, formamide, propylene carbonate, ethylene glycol, ethanolamine and 3,3,3-trifluoroethanol with n-heptane or n-hexane (10 systems), isopentyl ether (5 systems), 1,2-dichloroethane (2 systems) and 1-octanol (2 systems) of suitable low mutual solubility. The solvation parameter model is used to identify compounds with extreme partition constant values and to develop a selection guide based on the cluster analysis of the model system constants to identify biphasic systems for liquid–liquid extraction.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.061
      Issue No: Vol. 1527 (2017)
       
  • Development of Carbotrap B-packed needle trap device for determination of
           volatile organic compounds in air
    • Authors: Ali Poormohammadi; Abdulrahman Bahrami; Maryam Farhadian; Farshid Ghorbani Shahna; Alireza Ghiasvand
      Pages: 33 - 42
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Ali Poormohammadi, Abdulrahman Bahrami, Maryam Farhadian, Farshid Ghorbani Shahna, Alireza Ghiasvand
      Carbotrap B as a highly pure surface sorbent with excellent adsorption/desorption properties was packed into a stainless steel needle to develop a new needle trap device (NTD). The performance of the prepared NTD was investigated for sampling, pre-concentration and injection of benzene, toluene, ethyl benzene, o-xylene, and p-xylene (BTEX) into the column of gas chromatography-mass spectrometry (GC–MS) device. Response surface methodology (RSM) with central composite design (CCD) was also employed in two separate consecutive steps to optimize the sampling and device parameters. First, the sampling parameters such as sampling temperature and relative humidity were optimized. Afterwards, the RSM was used for optimizing the desorption parameters including desorption temperature and time. The results indicated that the peak area responses of the analytes of interest decreased with increasing sampling temperature and relative humidity. The optimum values of desorption temperature were in the range 265–273°C, and desorption time were in the range 3.4–3.8min. The limits of detection (LODs) and limits of quantitation (LOQs) of the studied analytes were found over the range of 0.03–0.04ng/mL, and 0.1–0.13ng/mL, respectively. These results demonstrated that the NTD packed with Carbotrap B offers a high sensitive procedure for sampling and analysis of BTEX in concentration range of 0.03–25ng/mL in air.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.062
      Issue No: Vol. 1527 (2017)
       
  • Single-step preparation of selected biological fluids for the high
           performance liquid chromatographic analysis of fat-soluble vitamins and
           antioxidants
    • Authors: Giacomo Lazzarino; Salvatore Longo; Angela Maria Amorini; Valentina Di Pietro; Serafina D’Urso; Giuseppe Lazzarino; Antonio Belli; Barbara Tavazzi
      Pages: 43 - 52
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Giacomo Lazzarino, Salvatore Longo, Angela Maria Amorini, Valentina Di Pietro, Serafina D’Urso, Giuseppe Lazzarino, Antonio Belli, Barbara Tavazzi
      Fat-soluble vitamins and antioxidants are of relevance in health and disease. Current methods to extract these compounds from biological fluids mainly need use of multi-steps and multi organic solvents. They are time-consuming and difficult to apply to treat simultaneously large sample number. We here describe a single-step, one solvent extraction of fat-soluble vitamins and antioxidants from biological fluids, and the chromatographic separation of all-trans-retinoic acid, 25-hydroxycholecalciferol, all-trans-retinol, astaxanthin, lutein, zeaxanthin, trans-β-apo-8′-carotenal, γ-tocopherol, β-cryptoxanthin, α-tocopherol, phylloquinone, lycopene, α-carotene, β-carotene and coenzyme Q10. Extraction is obtained by adding one volume of biological fluid to two acetonitrile volumes, vortexing for 60s and incubating for 60min at 37°C under agitation. HPLC separation occurs in 30min using Hypersil C18, 100×4.6mm, 5μm particle size column, gradient from 70% methanol+30% H2O to 100% acetonitrile, flow rate of 1.0ml/min and 37°C column temperature. Compounds are revealed using highly sensitive UV-VIS diode array detector. The HPLC method suitability was assessed in terms of sensitivity, reproducibility and recovery. Using the present extraction and chromatographic conditions we obtained values of the fat-soluble vitamins and antioxidants in serum from 50 healthy controls similar to those found in literature. Additionally, the profile of these compounds was also measured in seminal plasma from 20 healthy fertile donors. Results indicate that this simple, rapid and low cost sample processing is suitable to extract fat-soluble vitamins and antioxidants from biological fluids and can be applied in clinical and nutritional studies.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.053
      Issue No: Vol. 1527 (2017)
       
  • Unravelling the effects of multiple experimental factors in metabolomics,
           analysis of human neural cells with hydrophilic interaction liquid
           chromatography hyphenated to high resolution mass spectrometry
    • Authors: Víctor González-Ruiz; Julian Pezzatti; Adrien Roux; Luc Stoppini; Julien Boccard; Serge Rudaz
      Pages: 53 - 60
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Víctor González-Ruiz, Julian Pezzatti, Adrien Roux, Luc Stoppini, Julien Boccard, Serge Rudaz
      This work introduces a strategy for decomposing variable contributions within the data obtained from structured metabolomic studies. This approach was applied in the context of an in vitro human neural model to investigate biochemical changes related to neuroinflammation. Neural cells were exposed to the neuroinflammatory toxicant trimethyltin at different doses and exposure times. In the frame of an untargeted approach, cell contents were analysed using HILIC hyphenated with HRMS. Detected features were annotated at level 1 by comparison against a library of standards, and the 126 identified metabolites were analysed using a recently proposed chemometric tool dedicated to multifactorial Omics datasets, namely, ANOVA multiblock OPLS (AMOPLS). First, the total observed variability was decomposed to highlight the contribution of each effect related to the experimental factors. Both the dose of trimethyltin and the exposure time were found to have a statistically significant impact on the observed metabolic alterations. Cells that were exposed for a longer time exhibited a more mature and differentiated metabolome, whereas the dose of trimethyltin was linked to altered lipid pathways, which are known to participate in neurodegeneration. Then, these specific metabolic patterns were further characterised by analysing the individual variable contributions to each effect. AMOPLS was highlighted as a useful tool for analysing complex metabolomic data. The proposed strategy allowed the separation, quantitation and characterisation of the specific contribution of the different factors and the relative importance of every metabolite to each effect with respect to the total observed variability of the system.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.055
      Issue No: Vol. 1527 (2017)
       
  • On-line generation of third-order liquid
           chromatography–excitation-emission fluorescence matrix data.
           Quantitation of heavy-polycyclic aromatic hydrocarbons
    • Authors: Maira D. Carabajal; Juan A. Arancibia; Graciela M. Escandar
      Pages: 61 - 69
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Maira D. Carabajal, Juan A. Arancibia, Graciela M. Escandar
      For the first time, third-order liquid chromatography with excitation-emission fluorescence matrix detection (LC-EEFM) data were generated on-line and chemometrically processed for the simultaneous quantitation of the heavy-polycyclic aromatic hydrocarbons fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, and dibenz[a,h]anthracene. The applied experimental strategy is very simple, and is based on the reduction of the linear flow rate by fitting a larger diameter connecting-tube between the column outlet and the fluorimetric detector. In this way, EEFMs were successfully recorded on-line, without involving a large total analysis time. Because in the studied system quadrilinearity was fulfilled, four-way parallel factor (PARAFAC) analysis was applied for data processing. The second-order advantage, which is an intrinsic property of data of at least second-order, allowed the quantification of the analytes in interfering media. Moreover, resolution of the system with a high degree of collinearity was achieved thanks to the third-order advantage. In addition to a selectivity improvement, third-order/four-way calibration increased the sensitivity, with limits of detection in the range of 0.4−2.9ngmL−1. After a solid-phase extraction procedure with C18 membranes, considerably lower concentrations (between 0.033–2.70ngmL−1) were determined in real waters, with most recoveries in the range 90–106%.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.057
      Issue No: Vol. 1527 (2017)
       
  • Column-to-column packing variation of disposable pre-packed columns for
           protein chromatography
    • Authors: Susanne Schweiger; Stephan Hinterberger; Alois Jungbauer
      Pages: 70 - 79
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Susanne Schweiger, Stephan Hinterberger, Alois Jungbauer
      In the biopharmaceutical industry, pre-packed columns are the standard for process development, but they must be qualified before use in experimental studies to confirm the required performance of the packed bed. Column qualification is commonly done by pulse response experiments and depends highly on the experimental testing conditions. Additionally, the peak analysis method, the variation in the 3D packing structure of the bed, and the measurement precision of the workstation influence the outcome of qualification runs. While a full body of literature on these factors is available for HPLC columns, no comparable studies exist for preparative columns for protein chromatography. We quantified the influence of these parameters for commercially available pre-packed and self-packed columns of disposable and non-disposable design. Pulse response experiments were performed on 105 preparative chromatography columns with volumes of 0.2–20ml. The analyte acetone was studied at six different superficial velocities (30, 60, 100, 150, 250 and 500cm/h). The column-to-column packing variation between disposable pre-packed columns of different diameter-length combinations varied by 10–15%, which was acceptable for the intended use. The column-to-column variation cannot be explained by the packing density, but is interpreted as a difference in particle arrangement in the column. Since it was possible to determine differences in the column-to-column performance, we concluded that the columns were well-packed. The measurement precision of the chromatography workstation was independent of the column volume and was in a range of±0.01ml for the first peak moment and±0.007 ml2 for the second moment. The measurement precision must be considered for small columns in the range of 2ml or less. The efficiency of disposable pre-packed columns was equal or better than that of self-packed columns.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.059
      Issue No: Vol. 1527 (2017)
       
  • Standing wave design and optimization of a simulated moving bed
           chromatography for separation of xylobiose and xylose under the
           constraints on product concentration and pressure drop
    • Authors: Chung-gi Lee; Jae-Hwan Choi; Chanhun Park; Nien-Hwa Linda Wang; Sungyong Mun
      Pages: 80 - 90
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Chung-gi Lee, Jae-Hwan Choi, Chanhun Park, Nien-Hwa Linda Wang, Sungyong Mun
      The feasibility of a simulated moving bed (SMB) technology for the continuous separation of high-purity xylobiose (X2) from the output of a β-xylosidase X1→X2 reaction has recently been confirmed. To ensure high economical efficiency of the X2 production method based on the use of xylose (X1) as a starting material, it is essential to accomplish the comprehensive optimization of the X2-separation SMB process in such a way that its X2 productivity can be maximized while maintaining the X2 product concentration from the SMB as high as possible in consideration of a subsequent lyophilization step. To address this issue, a suitable SMB optimization tool for the aforementioned task was prepared based on standing wave design theory. The prepared tool was then used to optimize the SMB operation parameters, column configuration, total column number, adsorbent particle size, and X2 yield while meeting the constraints on X2 purity, X2 product concentration, and pressure drop. The results showed that the use of a larger particle size caused the productivity to be limited by the constraint on X2 product concentration, and a maximum productivity was attained by choosing the particle size such that the effect of the X2-concentration limiting factor could be balanced with that of pressure-drop limiting factor. If the target level of X2 product concentration was elevated, higher productivity could be achieved by decreasing particle size, raising the level of X2 yield, and increasing the column number in the zones containing the front and rear of X2 solute band.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.067
      Issue No: Vol. 1527 (2017)
       
  • Density dependence of retention factors of trans-stilbene oxide for chiral
           separation by supercritical fluid chromatography
    • Authors: Toshitaka Funazukuri; Yuna Ono; Junichi Sakabe; Chang Yi Kong
      Pages: 91 - 96
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Toshitaka Funazukuri, Yuna Ono, Junichi Sakabe, Chang Yi Kong
      Retention factors for two enantiomers of trans-stilbene oxide, k 1 and k 2, were measured with a chiral AD-H column using two syringe pumps to feed CO2 and methanol as a co-solvent at various temperatures, pressures and co-solvent mole fractions to determine the effects of these operating conditions on the retention factors. The retention factors k 1 and k 2 are for the (R,R)- and (S,S)-forms, respectively. When the isothermal compressibilities of a mixture of CO2 and MeOH were lower than 0.01, far from the critical locus of the CO2 and methanol mixture, both retention factors were well expressed with the solvent density and temperature with an average absolute relative deviation of 1–2%. In the vicinity of the critical locus, however, where the isothermal compressibilities were much larger than 0.01, the relationship between retention factor and density was complicated. Both retention factors were proportional to the isothermal compressibility, irrespective of methanol mole fraction at each temperature.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.029
      Issue No: Vol. 1527 (2017)
       
  • Simulated molecular-scale interaction of supercritical fluid mobile and
           stationary phases
    • Authors: Paul D. Siders
      Pages: 97 - 104
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Paul D. Siders
      In supercritical fluid chromatography, molecules from the mobile phase adsorb on the stationary phase. Stationary-phase alkylsilane-terminated silica surfaces might adsorb molecules at the silica, among the silanes, on a silane layer, or in pore space between surfaces. Mobile phases of carbon dioxide, pure and modified with methanol, and stationary phases were simulated at the molecular scale. Classical atomistic force fields were used in Gibbs-ensemble hybrid Monte Carlo calculations. Excess adsorption of pure carbon dioxide mobile phase peaked at fluid densities of 0.002–0.003Å−3. Mobile phase adsorption from 7% methanol in carbon dioxide peaked at lower fluid density. Methanol was preferentially adsorbed from the mixed fluid. Surface silanes prevented direct interaction of fluid-phase molecules with silica. Some adsorbed molecules mixed with tails of bonded silanes; some formed layers above the silanes. Much adsorption occurred by filling the space between surfaces in the stationary-phase model. The distribution in the stationary phase of methanol molecules from a modified fluid phase varied with pressure.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.056
      Issue No: Vol. 1527 (2017)
       
  • Corrigendum to “Gas chromatographic determination of polycyclic aromatic
           hydrocarbons in water and smoked rice samples after solid-phase
           microextraction using multiwalled carbon nanotube loaded hollow fiber”
           [J. Chromatogr. A 1374 (2014) 50–57]
    • Authors: Amir Abbas Matin; Pourya Biparva; Mohammad Gheshlaghi
      First page: 105
      Abstract: Publication date: 8 December 2017
      Source:Journal of Chromatography A, Volume 1527
      Author(s): Amir Abbas Matin, Pourya Biparva, Mohammad Gheshlaghi


      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.077
      Issue No: Vol. 1527 (2017)
       
  • Data acquisition workflows in liquid chromatography coupled to high
           resolution mass spectrometry-based metabolomics: Where do we stand'
    • Authors: François Fenaille; Pierre Barbier Saint-Hilaire; Kathleen Rousseau; Christophe Junot
      Pages: 1 - 12
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): François Fenaille, Pierre Barbier Saint-Hilaire, Kathleen Rousseau, Christophe Junot
      Typical mass spectrometry (MS) based untargeted metabolomics protocols are tedious as well as time- and sample-consuming. In particular, they often rely on “full-scan-only” analyses using liquid chromatography (LC) coupled to high resolution mass spectrometry (HRMS) from which metabolites of interest are first highlighted, and then tentatively identified by using targeted MS/MS experiments. However, this situation is evolving with the emergence of integrated HRMS based-data acquisition protocols able to perform multi-event acquisitions. Most of these protocols, referring to as data dependent and data independent acquisition (DDA and DIA, respectively), have been initially developed for proteomic applications and have recently demonstrated their applicability to biomedical studies. In this context, the aim of this article is to take stock of the progress made in the field of DDA- and DIA-based protocols, and evaluate their ability to change conventional metabolomic and lipidomic data acquisition workflows, through a review of HRMS instrumentation, DDA and DIA workflows, and also associated informatics tools.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.043
      Issue No: Vol. 1526 (2017)
       
  • Estimation of descriptors for hydrogen-bonding compounds from
           chromatographic and liquid-liquid partition measurements
    • Authors: Nicole Lenca; Sanka N. Atapattu; Colin F. Poole
      Pages: 13 - 22
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Nicole Lenca, Sanka N. Atapattu, Colin F. Poole
      Retention factors obtained by gas chromatography and reversed-phase liquid chromatography on varied columns and partition constants in different liquid-liquid partition systems are used to estimate WSU descriptor values for 36 anilines and N-heterocyclic compounds, 13 amides and related compounds, and 45 phenols and alcohols. These compounds are suitable for use as calibration compounds to characterize separation systems covering the descriptor space E=0.2–3, S=0.4–2.1, A=0–1.5, B=0.1–1.5, L=2.5–10.0 and V=0.5–2.2. Hydrogen-bonding properties are discussed in terms of structure, the possibility of induction effects, intramolecular hydrogen bonding and steric factors for anilines, amides, phenols and alcohols. The relationship between these parameters and observed descriptor values are difficult to predict from structure but facilitate improving the general occupancy of the descriptor space by creating incremental changes in hydrogen-bonding properties. It is verified that the compounds included in this study can be merged with an existing database of compounds recommended for characterizing separation systems.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.037
      Issue No: Vol. 1526 (2017)
       
  • Pseudo template molecularly imprinted polymer for determination of 14 kind
           of β-agonists in animal urine by ultra-high-performance liquid
           chromatography-tandem mass spectrometry
    • Authors: Decheng Suo; Ruiguo Wang; Peilong Wang; Xia Fan; Xiaoou Su
      Pages: 23 - 30
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Decheng Suo, Ruiguo Wang, Peilong Wang, Xia Fan, Xiaoou Su
      A pseudo template molecularly imprinted polymer (MIP) for selective extraction of β-agonists was prepared using 4-hydroxyphenethyl alcohol as pseudo template molecule, methyl acrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linker. Selectivity and adsorption capacity of prepared MIP were studied in detail. MIP selectively adsorbed 14 types of β-agonists. Advantages of the prepared polymer include non-template leakage in purification of target analytes and cheap cost. MIP was used to purify β-agonists in urine samples. The developed method was combined with ultra-performance liquid chromatography-tandem mass spectrometry. In optimum conditions, recoveries of the developed method ranged from 84.2% to 109.8% with low coefficients of variation at below 15%. Limits of detection and quantification for 14 target β-agonists in urine samples reached below 0.05ng/mL and 0.1ng/mL, respectively. The developed method based on MIP enrichment and purification were successfully applied to analysis of target analytes in 50 actual urine samples.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.09.076
      Issue No: Vol. 1526 (2017)
       
  • A modified quick, easy, cheap, effective, rugged, and safe cleanup method
           followed by liquid chromatography-tandem mass spectrometry for the rapid
           analysis of perchlorate, bromate and hypophosphite in flour
    • Authors: Yanping Xian; Xindong Guo; Xiangchang Hou; Li Wang; Yuluan Wu; Liwei Chen; Hao Dong; Bin Wang
      Pages: 31 - 38
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Yanping Xian, Xindong Guo, Xiangchang Hou, Li Wang, Yuluan Wu, Liwei Chen, Hao Dong, Bin Wang
      A selective, sensitive and useful method, based on modified QuEChERS cleanup combined with liquid chromatography-tandem mass spectrometry (LC–MS/MS) in the negative-ion electrospray ionization (ESI−) mode, was developed and validated for the simultaneous determination of three inorganic anions including perchlorate (ClO4 −), bromate (BrO3 −) and hypophosphite (H2PO2 −) in flour. The extraction parameters and LC–MS/MS conditions were optimized by single-factor experiment and sorbent combination in modified QuEChERS clean-up was optimized through response surface analysis. Three target analytes were separated on a normal-phase Phenomenex Luna Silica (2) column (150mm×2.0mm, 5μm, 100Å) with the mobile phase of a mixture of 5mmol/L ammonium acetate water solution and acetonitrile, detected by MS/MS under multiple reaction monitoring and quantified by external standard method. The developed method was validated in terms of the sensitivity, linearity, accuracy and precision, and matrix effect. The method showed a good linearity (R 2 >0.999) for all analytes in their respective concentration ranges. The ILOQs and MLOQs for perchlorate, bromate and hypophosphite were 0.1, 0.5, 5.0μg/L and 2.0, 6.0, 60.0μg/L, respectively. The average recoveries of three target analytes from the negative samples spiked at three different concentrations were in a range from 84.6% to 104.9%. The intra-day precision (n =6) and inter-day precision (n =5) of the target analytes were in the ranges of 2.9%–6.9% and 6.4%–8.2%. The matrix effect of this method was observed between 0.83 and 1.17 and was acceptable. The validated method was successfully applied to determine the concentrations of these inorganic anions in flour. Results found that perchlorate and hypophosphite were detected in 33 out of 50 and 7 out of 50 flour samples.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.047
      Issue No: Vol. 1526 (2017)
       
  • Development of an on-line solid phase extraction ultra-high-performance
           liquid chromatography technique coupled to tandem mass spectrometry for
           quantification of bisphenol S and bisphenol S glucuronide: Applicability
           to toxicokinetic investigations
    • Authors: Flore Grandin; Nicole Picard-Hagen; Véronique Gayrard; Sylvie Puel; Catherine Viguié; Pierre-Louis Toutain; Laurent Debrauwer; Marlène Z. Lacroix
      Pages: 39 - 46
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Flore Grandin, Nicole Picard-Hagen, Véronique Gayrard, Sylvie Puel, Catherine Viguié, Pierre-Louis Toutain, Laurent Debrauwer, Marlène Z. Lacroix
      Regulatory measures and public concerns regarding bisphenol A (BPA) have led to its replacement by structural analogues, such as Bisphenol S (BPS), in consumer products. At present, no toxicokinetic investigations have been conducted to assess the factors determining human internal exposure to BPS for subsequent risk assessment. Toxicokinetic studies require reliable analytical methods to measure the plasma concentrations of BPS and its main conjugated metabolite, BPS-glucuronide (BPS-G). An efficient on-line SPE-UPLC–MS/MS method for the simultaneous quantification of BPS and BPS-G in ovine plasma was therefore developed and validated in accordance with the European Medicines Agency guidelines for bioanalytical method validation. This method has a limit of quantification of 3ngmL−1 for BPS and 10ngmL−1 for BPS-G, an analytical capacity of 200 samples per day, and is particularly well suited to toxicokinetic studies. Use of this method in toxicokinetic studies in sheep showed that BPS, like BPA, is efficiently metabolized into its glucuronide form. However, the clearances and distributions of BPS and BPS-G were lower than those of the corresponding unconjugated and glucuroconjugated forms of BPA.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.020
      Issue No: Vol. 1526 (2017)
       
  • Profiling of a wide range of neurochemicals in human urine by
           very-high-performance liquid chromatography-tandem mass spectrometry
           combined with in situ selective derivatization
    • Authors: Wonwoong Lee; Na Hyun Park; Tae-Beom Ahn; Bong Chul Chung; Jongki Hong
      Pages: 47 - 57
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Wonwoong Lee, Na Hyun Park, Tae-Beom Ahn, Bong Chul Chung, Jongki Hong
      Development of a reliable analytical method of neurochemicals in biological fluids is important to discover potential biomarkers for the diagnosis, treatment and prognosis of neurological disorders. However, neurochemical profiling of biological samples is challenging because of highly different polarities between basic and acidic neurochemicals, low physiological levels, and high matrix interference in biological samples. In this study, an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method combined with in situ selective derivatization for comprehensive profiling of 20 neurochemicals in urine was developed for a wide range of neurochemicals. In situ selective derivatization greatly improved the peak capacity on a reversed-phase C18 column and sensitive mass detection in LC-ESI-MS/MS-positive ion mode due to reduction of the distinct physicochemical properties between acidic and basic neurochemicals. The MS/MS spectra of neurochemicals exhibited specific ions, such as losses of amine, methanol, or methyl formate molecules from protonated molecules, enabling selection of appropriate multiple reaction monitoring (MRM) ions for selective and sensitive detection. The developed method was validated in terms of linearity, limit of detection (LOD) and limit of quantification (LOQ), precision, accuracy, and recovery. The correlation coefficients (R2) of calibration curves were above 0.9961. The ranges of LODs and LOQs were 0.1–3.6ng/mL and 0.3–12.0ng/mL, respectively. The overall precision and accuracy were 0.52–16.74% and 82.26–118.17%, respectively. The method was successfully applied to simultaneously profile the metabolic pathways of tyrosine, tryptophan, and glutamate in Parkinson’s disease patient urine (PD, n=21) and control urine (n=10). Significant differences (P ≤0.01) between two groups in the activity of phenylethanolamine N-methyltransferase (PNMT) and alcohol dehydrogenase (ADH) were observed. In conclusion, this method provides reliable quantification of a wide range of neurochemicals in human urine and would be helpful for finding biomarkers related to specific neuronal diseases.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.021
      Issue No: Vol. 1526 (2017)
       
  • Definition and dynamic control of a continuous chromatography process
           independent of cell culture titer and impurities
    • Authors: Rebecca A. Chmielowski; Linda Mathiasson; Hans Blom; Daniel Go; Hanno Ehring; Heera Khan; Hong Li; Collette Cutler; Karol Lacki; Nihal Tugcu; David Roush
      Pages: 58 - 69
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Rebecca A. Chmielowski, Linda Mathiasson, Hans Blom, Daniel Go, Hanno Ehring, Heera Khan, Hong Li, Collette Cutler, Karol Lacki, Nihal Tugcu, David Roush
      Advances in cell culture technology have enabled the production of antibody titers upwards of 30g/L. These highly productive cell culture systems can potentially lead to productivity bottlenecks in downstream purification due to lower column loadings, especially in the primary capture chromatography step. Alternative chromatography solutions to help remedy this bottleneck include the utilization of continuous processing systems such as periodic counter-current chromatography (PCC). Recent studies have provided methods to optimize and improve the design of PCC for cell culture titers up to about 3g/L. This paper defines a continuous loading strategy for PCC that is independent of cell culture background and encompasses cell culture titers up to about 31g/L. Initial experimentation showed a challenge with determining a difference in change in UV280nm signal (ie. ΔUV) between cell culture feed and monoclonal antibody (mAb) concentration. Further investigation revealed UV280nm absorbance of the cell culture feedstock without antibody was outside of the linear range of detection for a given cell pathlength. Additional experimentation showed the difference in ΔUV for various cell culture feeds can be either theoretically predicted by Beer’s Law given a known absorbance of the media background and impurities or experimentally determined using various UV280nm cell pathlengths. Based on these results, a 0.35mm pathlength at UV280nm was chosen for dynamic control to overcome the background signal. The pore diffusion model showed good agreement with the experimental frontal analysis data, which resulted in definition of a ΔUV setpoint range between 20 and 70% for 3C-PCC experiments. Product quality of the elution pools was acceptable between various cell culture feeds and titers up to about 41g/L. Results indicated the following ΔUV setpoints to achieve robust dynamic control and maintain 3C-PCC yield: ∼20-45% for titers greater than 10g/L depending on UV absorbance of the HCCF and ∼45-70% for titers of up to 10g/L independent of UV absorbance of the HCCF. The strategy and results presented in this paper show column loading in a continuous chromatography step can be dynamically controlled independent of the cell culture feedstock and titer, and allow for enhanced process control built into the downstream continuous operations.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.030
      Issue No: Vol. 1526 (2017)
       
  • Development of immunosorbents coupled on-line to immobilized pepsin
           reactor and micro liquid chromatography–tandem mass spectrometry for
           analysis of butyrylcholinesterase in human plasma
    • Authors: Maud Bonichon; Audrey Combès; Charlotte Desoubries; Anne Bossée; Valérie Pichon
      Pages: 70 - 81
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Maud Bonichon, Audrey Combès, Charlotte Desoubries, Anne Bossée, Valérie Pichon
      Human butyrylcholinesterase (HuBuChE) has been widely used as a biomarker of exposure to organophosphorus (OPs) warfare agents. Indeed, intoxication by OPs can be proven by LC–MS/MS analysis of a specific HuBuChE nonapeptide on which OPs covalently bind. Therefore, we developed a fast, selective and sensitive on-line set-up for the analysis of HuBuChE from plasma that combines immunoextraction by anti-HuBuChE antibodies, pepsin digestion on Immobilized Enzyme Reactors (IMER) and microLC–MS/MS analysis of the target nonapeptide, FGESAGAAS. Two pepsin-based IMERs were prepared and characterized in terms of grafting and digestion yields and were coupled on-line to microLC–MS/MS analysis. In addition, immunosorbents were prepared by covalent grafting of three anti-HuBuChE antibodies on CNBr-sepharose and epoxy-polymethacrylate supports and packed in precolumns. The best antibody grafting yields were obtained with sepharose-based supports, with grafting yields up to 98%. B2 18-5 monoclonal antibody grafted on sepharose led to the best immunosorbent, with HuBuChE recovery close to 100%. The immunosorbent was introduced upstream of the on-line digestion set-up and immunoextraction of HuBuChE was achieved in 14min while digestion was performed in 20min, allowing detection of the target nonapeptide in less than 1h. The global recovery of the nonapeptide was higher than 42% using the best immunosorbent with a RSD value lower than 7% (n=3). Finally, the limit of quantification evaluated in plasma sample was 2fmol of nonapeptide. This value, corresponding to 0.5fmol of HuBuChE tetramer, is well below the average amount of HuBuChE tetramer in 50μL of plasma (590fmol).

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.033
      Issue No: Vol. 1526 (2017)
       
  • Development and validation of a method for the determination of regulated
           fragrance allergens by High-Performance Liquid Chromatography and Parallel
           Factor Analysis 2
    • Authors: Jessica Pérez-Outeiral; Saioa Elcoroaristizabal; Jose Manuel Amigo; Maider Vidal
      Pages: 82 - 92
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Jessica Pérez-Outeiral, Saioa Elcoroaristizabal, Jose Manuel Amigo, Maider Vidal
      This work presents the development and validation of a multivariate method for quantitation of 6 potentially allergenic substances (PAS) related to fragrances by ultrasound-assisted emulsification microextraction coupled with HPLC-DAD and PARAFAC2 in the presence of other 18 PAS. The objective is the extension of a previously proposed univariate method to be able to determine the 24 PAS currently considered as allergens. The suitability of the multivariate approach for the qualitative and quantitative analysis of the analytes is discussed through datasets of increasing complexity, comprising the assessment and validation of the method performance. PARAFAC2 showed to adequately model the data facing up different instrumental and chemical issues, such as co-elution profiles, overlapping spectra, unknown interfering compounds, retention time shifts and baseline drifts. Satisfactory quality parameters of the model performance were obtained (R2 ≥0.94), as well as meaningful chromatographic and spectral profiles (r≥0.97). Moreover, low errors of prediction in external validation standards (below 15% in most cases) as well as acceptable quantification errors in real spiked samples (recoveries from 82 to 119%) confirmed the suitability of PARAFAC2 for resolution and quantification of the PAS. The combination of the previously proposed univariate approach, for the well-resolved peaks, with the developed multivariate method allows the determination of the 24 regulated PAS.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.034
      Issue No: Vol. 1526 (2017)
       
  • Polymer monoliths with silver nanoparticles-cholesterol conjugate as
           stationary phases for capillary liquid chromatography
    • Authors: D. Grzywiński; M. Szumski; B. Buszewski
      Pages: 93 - 103
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): D. Grzywiński, M. Szumski, B. Buszewski
      Monoliths in fused-silica capillaries were prepared by an in-situ polymerization using glycidyl methacrylate (GMA) as a functional monomer and in the presence of different crosslinkers such as ethylene dimethacrylate (EDMA), trimethylolpropane trimethacrylate (TRIM), 1,6-hexanediol dimethacrylate (HEDMA), pentaerythritol tetraacrylate (PETeA), triethylene glycol dimethacrylate (TriEDMA), while azobisisobutyronitrile (AIBN) was an initiator. The monoliths’ surfaces were modified chemically with cystamine dihydrochloride, followed by immobilization of Ag-NPs the surface of which was functionalized with cholesterol cysteamine (Chol-SH). Such a new material enabled the separation of proteins in a reversed phase mode. The influence of the kind of a cross-linker and composition of the porogenic solutions on the porosity and separation properties of the obtained polymers was investigated and discussed. It was found that the amount of Ag-NPs embedded on the monoliths’ surfaces depended on the porous properties of the monoliths, which was directly connected with the kind of the cross-linkers used. For the determination of the amount of the attached Ag-NPs the thermogravimetric analysis was used and additionally the ISEC method as a comparative method was also proposed. It was found that the maximum amount (about 20% by weight) of the 10nm Ag-NPs was attached to the poly(GMA-EDMA) and poly(GMA-TRIM) monoliths.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.039
      Issue No: Vol. 1526 (2017)
       
  • Reversed-phase chromatography with large pore superficially porous
           particles for high throughput immunoglobulin G2 disulfide isoform
           separation
    • Authors: Bingchuan Wei; Bing Zhang; Barry Boyes; Yonghua Taylor Zhang
      Pages: 104 - 111
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Bingchuan Wei, Bing Zhang, Barry Boyes, Yonghua Taylor Zhang
      Reversed-phase liquid chromatography (RPLC) has been commonly used in IgG2 disulfide isoforms analysis. Recently, the columns packed with large pore superficially porous particles (SPP) have become available commercially. This work explores the application of this SPP technology in IgG2 disulfide isoforms separation. A high throughput and improved resolution RPLC method is developed with the optimization of column selection, gradient, temperature and flow rate. Compared with the small particles RP-UHPLC columns, large pore SPP columns provide unique selectivity and several new peaks were resolved and identified to be the free thiol variants of the IgG2 disulfide isoforms. The optimized method enables the detailed characterization of cysteines related variants in a single and fast method.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.040
      Issue No: Vol. 1526 (2017)
       
  • Quantification of steroid hormones in human serum by liquid
           chromatography-high resolution tandem mass spectrometry
    • Authors: Silke Matysik; Gerhard Liebisch
      Pages: 112 - 118
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Silke Matysik, Gerhard Liebisch
      A limited specificity is inherent to immunoassays for steroid hormone analysis. To improve selectivity mass spectrometric analysis of steroid hormones by liquid chromatography-tandem mass spectrometry (LC–MS/MS) has been introduced in the clinical laboratory over the past years usually with low mass resolution triple-quadrupole instruments or more recently by high resolution mass spectrometry (HR-MS). Here we introduce liquid chromatography-high resolution tandem mass spectrometry (LC–MS/HR-MS) to further increase selectivity of steroid hormone quantification. Application of HR-MS demonstrates an enhanced selectivity compared to low mass resolution. Separation of isobaric interferences reduces background noise and avoids overestimation. Samples were prepared by automated liquid–liquid extraction with MTBE. The LC–MS/HR-MS method using a quadrupole-Orbitrap analyzer includes eight steroid hormones i.e. androstenedione, corticosterone, cortisol, cortisone, 11-deoxycortisol, 17-hydroxyprogesterone, progesterone, and testosterone. It has a run-time of 5.3min and was validated according to the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) guidelines. For most of the analytes coefficient of variation were 10% or lower and LOQs were determined significantly below 1ng/ml. Full product ion spectra including accurate masses substantiate compound identification by matching their masses and ratios with authentic standards. In summary, quantification of steroid hormones by LC–MS/HR-MS is applicable for clinical diagnostics and holds also promise for highly selective quantification of other small molecules.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.042
      Issue No: Vol. 1526 (2017)
       
  • Multiresidue determination of pesticides in crop plants by the quick,
           easy, cheap, effective, rugged, and safe method and ultra-high-performance
           liquid chromatography tandem mass spectrometry using a calibration based
           on a single level standard addition in the sample
    • Authors: Mariela S. Viera; Tiele M. Rizzetti; Maiara P. de Souza; Manoel L. Martins; Osmar D. Prestes; Martha B. Adaime; Renato Zanella
      Pages: 119 - 127
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Mariela S. Viera, Tiele M. Rizzetti, Maiara P. de Souza, Manoel L. Martins, Osmar D. Prestes, Martha B. Adaime, Renato Zanella
      In this study, a QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method, optimized by a 23 full factorial design, was developed for the determination of 72 pesticides in plant parts of carrot, corn, melon, rice, soy, silage, tobacco, cassava, lettuce and wheat by ultra-high-performance liquid chromatographic tandem mass spectrometry (UHPLC–MS/MS). Considering the complexity of these matrices and the need of use calibration in matrix, a new calibration approach based on single level standard addition in the sample (SLSAS) was proposed in this work and compared with the matrix-matched calibration (MMC), the procedural standard calibration (PSC) and the diluted standard addition calibration (DSAC). All approaches presented satisfactory validation parameters with recoveries from 70 to 120% and relative standard deviations≤20%. SLSAS was the most practical from the evaluated approaches and proved to be an effective way of calibration. Method limit of detection were between 4.8 and 48μgkg−1 and limit of quantification were from 16 to 160μgkg−1. Method application to different kinds of plants found residues of 20 pesticides that were quantified with z-scores values≤2 in comparison with other calibration approaches. The proposed QuEChERS method combined with UHPLC–MS/MS analysis and using an easy and effective calibration procedure presented satisfactory results for pesticide residues determination in different crop plants and is a good alternative for routine analysis.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.048
      Issue No: Vol. 1526 (2017)
       
  • Method optimization for drug impurity profiling in supercritical fluid
           chromatography: Application to a pharmaceutical mixture
    • Authors: Charlene Muscat Galea; David Didion; David Clicq; Debby Mangelings; Yvan Vander Heyden
      Pages: 128 - 136
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Charlene Muscat Galea, David Didion, David Clicq, Debby Mangelings, Yvan Vander Heyden
      A supercritical chromatographic method for the separation of a drug and its impurities has been developed and optimized applying an experimental design approach and chromatogram simulations. Stationary phase screening was followed by optimization of the modifier and injection solvent composition. A design-of-experiment (DoE) approach was then used to optimize column temperature, back-pressure and the gradient slope simultaneously. Regression models for the retention times and peak widths of all mixture components were built. The factor levels for different grid points were then used to predict the retention times and peak widths of the mixture components using the regression models and the best separation for the worst separated peak pair in the experimental domain was identified. A plot of the minimal resolutions was used to help identifying the factor levels leading to the highest resolution between consecutive peaks. The effects of the DoE factors were visualized in a way that is familiar to the analytical chemist, i.e. by simulating the resulting chromatogram. The mixture of an active ingredient and seven impurities was separated in less than eight minutes. The approach discussed in this paper demonstrates how SFC methods can be developed and optimized efficiently using simple concepts and tools.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.036
      Issue No: Vol. 1526 (2017)
       
  • High performance thin-layer chromatography–mass spectrometry enables
           reliable analysis of physalins in different plant parts of Physalis
           alkekengi L.
    • Authors: Eva Kranjc; Alen Albreht; Irena Vovk; Vesna Glavnik
      Pages: 137 - 150
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Eva Kranjc, Alen Albreht, Irena Vovk, Vesna Glavnik
      We developed first HPTLC and HPTLC–MS/MS methods which enable characterization of structurally similar and complex biologically active compounds – physalins – from crude extracts of Chinese lantern (Physalis alkekengi L.). Separation on HPTLC silica gel plates developed with ethyl acetate–toluene–formic acid (7:3:0.2, v/v) enabled densitometric screening of physalins in absorption and, after post-chromatographic derivatization with sulfuric acid reagent, also in fluorescence mode. Compared to existing (U)HPLC methods, in this case TLC provides an alternative selectivity, better sensitivity and higher resolution, which was exemplified by the separation of physalin L standard and its impurity, identified as 2,3,25,27-tetrahydrophysalin A. Strong ion suppression caused by the developing solvent additive – formic acid – was efficiently solved by two successive plate pre-developments with methanol–formic acid (9:1, v/v) and methanol. This significantly improved the sensitivity of HPTLC–MS/MS method, but also required a slightly modified developing solvent ethyl acetate–toluene–formic acid (6:4:0.2, v/v). Simultaneous hyphenation of HPTLC with a triple quadrupole and an ion trap mass analyzer enabled a reliable and straightforward non-targeted characterization of physalins from the same chromatographic zone (band) and determination of physalin types. The performance of developed HPTLC-densitometric and HPTLC–MS/MS methods was demonstrated by the analysis of physalins from the aqueous extracts, prepared by an optimized fast and simple extraction method under reflux. Variations in physalin profiles and abundances in different parts of P. alkekengi L. harvested at different stages of maturity were observed. This indicates that not all parts of the plant, or plant as a whole, are appropriate for specific medicinal applications. Husks are proposed as the most suitable plant part for P. alkekengi L. quality control, because they exhibited the most obvious MS2 fingerprints of physalins with minimal interferences.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.09.070
      Issue No: Vol. 1526 (2017)
       
  • Thin-layer chromatography coupled with high performance liquid
           chromatography for determining tetrabromobisphenol A/S and their
           derivatives in soils
    • Authors: Aifeng Liu; Zhaoshuang Shen; Yong Tian; Rongguang Shi; Yi Liu; Zongshan Zhao; Mo Xian
      Pages: 151 - 156
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Aifeng Liu, Zhaoshuang Shen, Yong Tian, Rongguang Shi, Yi Liu, Zongshan Zhao, Mo Xian
      As brominated flame retardants (BFRs), tetrabromobisphenol A/S (TBBPA/S) and their derivatives have raised wide concerns owing to their widely usage, distributions and adverse effects on human health, thus monitoring these BFRs was urgently needed. In this study, a rapid and cost-effective method based on thin-layer chromatography (TLC) sample pre-treatment coupled with high performance liquid chromatography-diode array detector (HPLC-DAD) (UV=214nm) was developed for determining TBBPA/S and their derivatives in soils, including TBBPA, TBBPA bis(allyl ether) (TBBPA-BAE), TBBPA bis(2,3-dibromopropyl ether) (TBBPA-BDBPE), TBBPS bis(allyl ether) (TBBPS-BAE) and TBBPS bis(2,3-dibromopropyl ether) (TBBPS-BDBPE). The method detection limits (MDLs) and the method quantification limits (MQLs) for these BFRs ranged from 0.023 to 0.087μgg−1 dw and 0.076–0.29μgg−1 dw, respectively. The recoveries were 41–108% and both RSD of repeatability and intermediate precision were less than 11%. The developed method presented good performance for analyzing natural soil samples collected from BFRs industrial park, suggesting its great application potential for monitoring environmental TBBPA/S and their derivatives.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.045
      Issue No: Vol. 1526 (2017)
       
  • Immunological analysis of food proteins using high-performance thin-layer
           chromatography-immunostaining
    • Authors: Lena Morschheuser; Kathrin Mink; Ramona Horst; Constanze Kallinich; Sascha Rohn
      Pages: 157 - 166
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): Lena Morschheuser, Kathrin Mink, Ramona Horst, Constanze Kallinich, Sascha Rohn
      The chromatographic analysis of intact proteins is still challenging, especially when biological functions as antigenicity of proteins or peptides are in the focus. Traditional immunoassays provide information about the entirety of antigenic proteins/peptides, e.g., in ELISA assays. On the other hand, when focusing on the investigation of (cross) reactivity of antibodies, Western blot following gel-electrophoresis represents the method of choice. However, gel-electrophoresis is limited by the molecular weight and therefore, not suitable for peptides ≤3kDa or proteins ≥250kDa. Furthermore, for gaining detailed information about the protein sequence (e.g., via mass spectrometric analysis), a so called in-gel digest needs to be performed following electrophoretic separation and is therefore elaborate and accompanied by a significant loss of structural, and even more severe, conformational information. Here, protein analysis using HPTLC seems to be a promising alternative due to the high level of variability regarding the chromatographic system (multiple mobile and stationary phases, even mixed) and manifold detection as well as hyphenation possibilities. This study exemplarily focused on the immunological investigation of proteins in milk following thin-layer chromatographic separation. The detection of these antigens is mandatory, as they might trigger allergenic reactions in sensitized people. Besides the proof of its applicability on different stationary phase materials, the newly developed immunoassay can be used as an approach for semi-quantitative estimation of antigenic proteins. In addition to the analysis of intact food allergens, also analyzing peptides thereof is worth considering which can be realized using HPTLC-immunostaining as well.

      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.046
      Issue No: Vol. 1526 (2017)
       
  • Corrigendum to “Non-invasive metabolomics for improved determination of
           embryonic sex markers in chemically defined culture medium” [J.
           Chromatogr. A 1474 (2016) 138–144]
    • Authors: E. Gómez; M. Muñoz; C. Simó; C. Ibáñez; S. Carrocera; D. Martín-González; A. Cifuentes
      First page: 167
      Abstract: Publication date: 1 December 2017
      Source:Journal of Chromatography A, Volume 1526
      Author(s): E. Gómez, M. Muñoz, C. Simó, C. Ibáñez, S. Carrocera, D. Martín-González, A. Cifuentes


      PubDate: 2017-11-09T01:34:44Z
      DOI: 10.1016/j.chroma.2017.10.058
      Issue No: Vol. 1526 (2017)
       
  • Online analysis of five organic ultraviolet filters in environmental water
           samples using magnetism-enhanced monolith-based in-tube solid phase
           microextraction coupled with high-performance liquid chromatography
    • Authors: Meng Mei; Xiaojia Huang
      Pages: 1 - 9
      Abstract: Publication date: 24 November 2017
      Source:Journal of Chromatography A, Volume 1525
      Author(s): Meng Mei, Xiaojia Huang
      Due to the endocrine disrupting properties, organic UV filters have been a great risk for humans and other organisms. Therefore, development of accurate and effective analytical methods is needed for the determination of UV filters in environmental waters. In this work, a fast, sensitive and environmentally friendly method combining magnetism-enhanced monolith-based in-tube solid phase microextraction with high-performance liquid chromatography with diode array detection (DAD) (ME-MB-IT/SPME-HPLC-DAD) for the online analysis of five organic UV filters in environmental water samples was developed. To extract UV filters effectively, an ionic liquid-based monolithic capillary column doped with magnetic nanoparticles was prepared by in-situ polymerization and used as extraction medium of online ME-MB-IT/SPME-HPLC-DAD system. Several extraction conditions including the intensity of magnetic field, sampling and desorption flow rate, volume of sample and desorption solvent, pH value and ionic strength of sample matrix were optimized thoroughly. Under the optimized conditions, the extraction efficiencies for five organic UV filters were in the range of 44.0–100%. The limits of detection (S/N=3) and limits of quantification (S/N=10) were 0.04–0.26μg/L and 0.12–0.87μg/L, respectively. The precisions indicated by relative standard deviations (RSDs) were less than 10% for both intra- and inter-day variabilities. Finally, the developed method was successfully applied to the determination of UV filters in three environmental water samples and satisfactory results were obtained.

      PubDate: 2017-11-01T12:06:20Z
      DOI: 10.1016/j.chroma.2017.09.065
      Issue No: Vol. 1525 (2017)
       
  • A single–step synthesized supehydrophobic melamine formaldehyde foam for
           trace determination of volatile organic pollutants
    • Authors: Habib Bagheri; Shakiba Zeinali; Mohammad Yahya Baktash
      Pages: 10 - 16
      Abstract: Publication date: 24 November 2017
      Source:Journal of Chromatography A, Volume 1525
      Author(s): Habib Bagheri, Shakiba Zeinali, Mohammad Yahya Baktash
      Superhydrophobic materials have attracted many attentions in recent years while their application in sample preparation remained almost intact. In this project, a rough surface of melamine formaldehyde foam was silanized by chemical deposition of trichloromethylsilane to form a highly porous and superhydrophobic material, presumably a suitable medium for extracting non–polar compounds such as benzene and its methyl derivatives. The prepared sorbent was packed in a needle for the headspace needle–trap microextraction of benzene, toluene, ethylbenzene and xylenes (BTEX). Major parameters associated with the extraction/desorption processes were considered for optimization. Under the optimized condition, the linear dynamic range was from 20 to 1000ngL−1 (R2 >0.98). For evaluating the method precision, inter–day, intra–day and needle–to–needle relative standard deviations (RSD%) were calculated (<13%) for water samples spiked at 500ngL−1 of BTEX. The LOD values were in the range of 5–10ngL−1 using gas chromatography–flame ionization detector (GC-FID). Finally, hookah water was considered as suspicious real sample, assumed to contain volatile organic pollutants. Among these pollutants, toluene was identified, at the concentration level of 439ngL−1, in one of the hookah samples while benzene was detectable at much lower level. Also, some other organic pollutants were identified in the smoke and hookah water using GC–mass spectrometry (GC–MS). In addition, the suspicious BTEX–containing samples from petrochemical waste water of Asalooye (Persian Gulf) were analyzed.

      PubDate: 2017-11-01T12:06:20Z
      DOI: 10.1016/j.chroma.2017.10.012
      Issue No: Vol. 1525 (2017)
       
  • Adsorption of marine phycotoxin okadaic acid on a covalent organic
           framework
    • Authors: Laura M. Salonen; Sara R. Pinela; Soraia P.S. Fernandes; João Louçano; Enrique Carbó-Argibay; Marisa P. Sarriá; Carlos Rodríguez-Abreu; João Peixoto; Begoña Espiña
      Pages: 17 - 22
      Abstract: Publication date: 24 November 2017
      Source:Journal of Chromatography A, Volume 1525
      Author(s): Laura M. Salonen, Sara R. Pinela, Soraia P.S. Fernandes, João Louçano, Enrique Carbó-Argibay, Marisa P. Sarriá, Carlos Rodríguez-Abreu, João Peixoto, Begoña Espiña
      Phycotoxins, compounds produced by some marine microalgal species, can reach high concentrations in the sea when a massive proliferation occurs, the so-called harmful algal bloom. These compounds are especially dangerous to human health when concentrated in the digestive glands of seafood. In order to generate an early warning system to alert for approaching toxic outbreaks, it is very important to improve monitoring methods of phycotoxins in aquatic ecosystems. Solid-phase adsorption toxin tracking devices reported thus far based on polymeric resins have not been able to provide an efficient harmful algal bloom prediction system due to their low adsorption capabilities. In this work, a water-stable covalent organic framework (COF) was evaluated as adsorbent for the hydrophobic toxin okadaic acid, one of the most relevant marine toxins and the parental compound of the most common group of toxins responsible for the diarrhetic shellfish poisoning. Adsorption kinetics of okadaic acid onto the COF in seawater showed that equilibrium concentration was reached in only 60min, with a maximum experimental adsorption of 61mgg−1. Desorption of okadaic acid from the COF was successful with both 70% ethanol and acetonitrile as solvent, and the COF material could be reused with minor losses in adsorption capacity for three cycles. The results demonstrate that COF materials are promising candidates for solid-phase adsorption in water monitoring devices.

      PubDate: 2017-11-01T12:06:20Z
      DOI: 10.1016/j.chroma.2017.10.017
      Issue No: Vol. 1525 (2017)
       
  • A low-cost biosorbent-based coating for the highly sensitive determination
           of organochlorine pesticides by solid-phase microextraction and gas
           chromatography-electron capture detection
    • Authors: Sângela Nascimento do Carmo; Josias Merib; Adriana Neves Dias; Joni Stolberg; Dilma Budziak; Eduardo Carasek
      Pages: 23 - 31
      Abstract: Publication date: 24 November 2017
      Source:Journal of Chromatography A, Volume 1525
      Author(s): Sângela Nascimento do Carmo, Josias Merib, Adriana Neves Dias, Joni Stolberg, Dilma Budziak, Eduardo Carasek
      In this study, an environmentally friendly and low-cost biosorbent coating was evaluated, for the first time, as the extraction phase for solid-phase microextraction (SPME) supported on a nitinol alloy. The characterization of the new fiber was performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The applicability of the biosorbent-based fiber in the determination of δ-hexachlorocyclohexane, aldrin, heptachlor epoxide, α-endosulfan, endrin and 4,4′-DDD in water samples was verified, with separation/detection by gas chromatography coupled to electron capture detection (GC-ECD). The influencing parameters (temperature, extraction time and ionic strength) were optimized simultaneously using a central composite design. The optimum conditions were: extraction time of 80min at 80°C and sodium chloride concentration of 15% (w/v). Satisfactory analytical performance was achieved with limits of detection (LOD) between 0.19 and 0.71ngL−1 and limits of quantification (LOQ) between 0.65 and 2.38ngL−1. The relative recoveries for the analytes were determined using river and lake water samples spiked at different concentrations and ranged from 60% for α-endosulfan to 113% for δ-hexachlorocyclohexane, with relative standard deviations (RSD) lower than 21%. The fiber-to-fiber reproducibility (n=3) was also evaluated and the RSD was lower than 14%. The extraction efficiency obtained for the proposed biosorbent coating was compared to a commercially available DVB/Car/PDMS coating. The proposed fiber provided very promising results, including LODs at the level of parts per trillion and highly satisfactory thermal and mechanical stability.

      PubDate: 2017-11-01T12:06:20Z
      DOI: 10.1016/j.chroma.2017.10.018
      Issue No: Vol. 1525 (2017)
       
  • Magnetic covalent triazine framework for rapid extraction of phthalate
           esters in plastic packaging materials followed by gas chromatography-flame
           ionization detection
    • Authors: Zijun Yan; Man He; Beibei Chen; Bo Gui; Cheng Wang; Bin Hu
      Pages: 32 - 41
      Abstract: Publication date: 24 November 2017
      Source:Journal of Chromatography A, Volume 1525
      Author(s): Zijun Yan, Man He, Beibei Chen, Bo Gui, Cheng Wang, Bin Hu
      Covalent triazine frameworks (CTFs), featuring with high surface area, good thermal, chemical and mechanical stability, are good adsorbents in sample pretreatment. Herein, magnetic CTFs/Ni composite was prepared by in situ reduction of nickel ions on CTFs matrix with a solvothermal method. The prepared CTFs/Ni composite exhibited good preparation reproducibility, high chemical stability, and high extraction efficiency for targeted phthalate esters (PAEs) due to π-π interaction and hydrophobic effect. The porous structure of CTFs/Ni composite benefited the fast transfer of target PAEs from aqueous solution to the adsorbents, and the integrated magnetism contributed to the rapid separation of adsorbents from sample and elution solution. Based on it, a novel method of magnetic solid phase extraction (MSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the analysis of PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexl phthalate (DEHP), and di-n-octyl phthalate (DNOP) in plastic packaging materials. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) for six PAEs were found to be in the range of 0.024-0.085mg/kg. The linear range was 0.32–16mg/kg for DMP, DEP, 0.08–80mg/kg for DBP, 0.16–32mg/kg for BBP, DEHP, and 0.32–32mg/kg for DNOP, respectively. The enrichment factors ranged from 59 to 88-fold (theoretical enrichment factor was 133-fold). The proposed method was successfully applied to the analysis of PAEs in various plastic packaging materials with recoveries in the range of 70.6-119% for the spiked samples. This method is characterized with short operation time, high sensitivity, low consumption of harmful organic solvents and can be extended to the analysis of other trace aromatic compounds.

      PubDate: 2017-11-01T12:06:20Z
      DOI: 10.1016/j.chroma.2017.10.025
      Issue No: Vol. 1525 (2017)
       
  • A molybdenum disulfide/reduced graphene oxide fiber coating coupled with
           gas chromatography–mass spectrometry for the saponification-headspace
           solid-phase microextraction of polychlorinated biphenyls in food
    • Authors: Fangying Lv; Ning Gan; Yuting Cao; You Zhou; Rongjie Zuo; Youren Dong
      Pages: 42 - 50
      Abstract: Publication date: 24 November 2017
      Source:Journal of Chromatography A, Volume 1525
      Author(s): Fangying Lv, Ning Gan, Yuting Cao, You Zhou, Rongjie Zuo, Youren Dong
      In this work, the molybdenum disulfide/reduced graphene oxide (MoS2/RGO) composite material was synthesized as a fiber coating to extract seven indicator polychlorinated biphenyls (PCBs; PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) present in food via a saponification-headspace solid-phase microextraction assay (saponification-HS-SPME). The MoS2/RGO coating was prepared and deposited on a stainless steel wire with the help of a silicone sealant and used as an SPME fiber. The alkali solution dissolved the fat and helped in releasing the PCBs present in milk to the headspace for extraction under 100°C. Following desorption in the inlet, the targets were quantified by gas chromatography-mass spectrometry. The effects of sorbent dosage, extraction time, added salts, and stirring rate on the extraction efficiency were investigated. The new coating was able to adsorb a higher amount of analytes, which was about 1.1–2.9 times in comparison with the commercially available SPME fiber (coated with divinylbenzene/carboxen/polydimethylsiloxane). It also showed the highest adsorption capability toward PCBs, which was 1.5–2.7 times that of the prepared RGO modified fiber. Moreover, MoS2 also showed a strong affinity toward PCBs in a manner similar to its affinity for graphene. The developed method is simple and environmentally friendly as it does not require any organic solvents. Furthermore, it exhibits good sensitivity with detection limits less than 0.1ngmL−1, linearity (0.25–100ngmL−1), and reproducibility (relative standard deviation below 10% for n=3). The novel SPME fibers are inexpensive, reusable, and can be easily prepared and manipulated. In addition, the saponification-HS-SPME assay was also found to be suitable for screening persistent organic pollutants in dairy products.

      PubDate: 2017-11-01T12:06:20Z
      DOI: 10.1016/j.chroma.2017.10.026
      Issue No: Vol. 1525 (2017)
       
 
 
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