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Journal of chromatography
Elesevier
Journal of chromatography

Elesevier

0021-9673

Journal of chromatography/Journal Journal of chromatographySCIISTPCCR
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    Optimization and validation of direct gas chromatography-mass spectrometry method for simultaneous quantification of ten short-chain acids in rat feces

    Wang, Si-YuLiu, HuiZhou, Shan-ShanZhang, Wei...
    10页
    查看更多>>摘要：Short-chain fatty acids (SCFAs) play key roles in maintaining health and treating disease. Quantification of important fecal SCFAs is necessary to facilitate the clarification of their biological roles. However, the existing quantifying methods mainly depend on complicated precolumn derivatization, and/or are unable to determine formic acid, a SCFA commonly associated with toxicity. In this study, a direct gas chromatography-mass spectrometry (GC-MS) method for simultaneous quantification of ten SCFAs including formic acid in rat feces was developed. The approach was optimized in terms of chromatographic and spectrometric conditions as well as sample preparation. DB-FFAP capillary column with temperature programming was used to get baseline separation and symmetrical peak shape of SCFAs without precolumn derivatization in a relatively short running time (8 min). Multiple reaction monitoring (MRM) scan mode was employed to enhance the sensitivity and selectivity of SCFAs. Acidification with 50% HCl and immediate extraction with diethyl ether were utilized to achieve sample preparation of ten SCFAs from feces. Furthermore, the developed method was validated with wide linear range, high sensitivity and precision, low matrix effect and acceptable accuracy. The established method was successfully applied to compare the contents of fecal SCFAs between normal and immunosuppressed animal models. (c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Superficially capped amino metal-organic framework for efficient solid-phase microextraction of perfluorinated alkyl substances

    Ye, Yu-XinZheng, JuanTong, YuanjunHu, Yalan...
    8页
    查看更多>>摘要：Perfluorinated alkyl substances (PFASs) were ubiquitously in the surface and groundwater. It is crucial and urgent to develop a rapid and ultrasensitive analysis method for the quantification of trace-level PFASs. Herein, a highly hydrophobic sorbent by capping phenylsilane groups on the surfaces of NH2-UiO-66(Zr) nanocrystals was used for efficient solid-phase microextraction (SPME) of PFASs in water samples. It was found that the superficially capped nanocrystals (NH2-UiO-66(Zr)-hp) exhibited both faster extraction kinetics and higher enrichment capacity than the non-capped nanocrystals. The extraction of eleven kinds of PFASs by NH2-UiO-66(Zr)-hp fiber reached equilibrium in 20 min. The enrichment factors of the NH2-UiO-66(Zr)-hp fiber ranged from 6.5 to 48, with a preference for long-chain PFASs over short-chain PFASs. It was proposed that superficial capping eliminated competitive moisture adsorption on the surfaces of the non-capped nanocrystals, thus facilitating the adsorption of PFASs through hydrophobic interaction. By using this new sorbent, the limits of detection of the SPME method as low as 0.035 to 0.616 ng.L-1 were achieved for the target PFASs. The recoveries of PFASs in the environmental water samples were 80.9%-120%. This study presents a new strategy for developing an efficient sorbent for PFASs by surface hydrophobic modification.(c) 2022 Elsevier B.V. All rights reserved
      原文链接:
    • NSTL
    • Elsevier

    Amalgamation of comparative protein modeling with quantitative structure-retention relationship for prediction of the chromatographic behavior of peptides

    Borkar, Maheshkumar R.Coutinho, Evans C.
    7页
    查看更多>>摘要：Peptide therapeutics plays a prominent role in medical practice. Both peptides and proteins have been used in several disease conditions like diabetes, cancer, bacterial infections etc. The optimization of a peptide library is a time consuming and expensive chore. The tools of computational chemistry offer a way to optimize the properties of peptides. Quantitative Structure Retention (Chromatographic) Relationships (QSRR) is a powerful tool which statistically derives relationships between chromatographic parameters and descriptors that characterize the molecular structure of analytes. In this paper, we show how Comparative Protein M odelingQ uantitative S tructure R etention R elationship (acronym ComProM-QSRR) can be used to predict the retention time of peptide sequences. This formalism is founded on our earlier published QSAR methodology HomoSAR. ComProM-QSRR can recognize and distinguish the contribution of amino acids at specific positions in the peptide sequences to the retention phenomena through their related physicochemical properties. This study firmly establishes the fact that this approach can be pragmatically used to predict the retention time to all classes of peptides regardless of size or sequence.
      原文链接:
    • NSTL
    • Elsevier

    Comprehensive two-dimensional gas chromatography using direct flow modulation to extend the secondary dimension separation time

    Cai, HuaminStearns, Stanley D.
    13页
    查看更多>>摘要：A simple direct flow modulator has been constructed and evaluated. This modulator employs a tee to connect the primary and secondary columns so that a negative pulsed flow can be introduced through the third leg of the connector into the joint between the columns. The modulation gas pressure can be adjusted to allow a longer recovery time for the primary column flow after the reversal initiated at the beginning of a modulation period, resulting in a longer secondary separation time. In this study, a 120 s secondary separation time has been achieved. That is long enough for use with a longer secondary column and secondary temperature ramping. Factors which affect the secondary peak width at base (W-2(b)), including modulation pulse width, modulation period, and inlet/modulation pressure differential, have also been investigated. Our results indicate that all three of these factors have a large impact on 2Wb, since they all affect the amount of primary effluent loaded onto the secondary dimension. Various sizes of tee connectors - 360 mu m, 1/32 '', and 1/16 ''- gives the best performance in terms of less peak tailing and narrower W-2(b). The time needed to switch from one dimension GC to GC xGC for this method is discussed, and several methods to shorten the waiting time have been proposed. Applications of this method on gasoline and reference gas oil standard have been demonstrated. (C) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Rapid separation of americium from complex matrices using solvent impregnated triazine extraction chromatography resins

    Mahmoud, JoeHigginson, MatthewThompson, PaulGilligan, Christopher...
    9页
    查看更多>>摘要：Several novel extraction chromatography resins (EXC) have been synthesised by solvent impregna-tion of the triazine ligands 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo[1,2,4]triazin-3-yl)-2,2'- bipyridine (CyMe4BTBP) and 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]triazin-3-yl)-1,10-phenanthroline (CyMe(4)BTPhen) into Amberlite XAD7 and Amberchrom CG300 polymer supports. The resins have been physically characterised by a suite of spectroscopic, analytical and imaging techniques. The resins have also been evaluated in terms of their ability to selectively extract americium from com-plex matrices intended to simulate those typical of spent nuclear fuel raffinate, environmental samples and nuclear forensics samples. The resins have been compared with previously reported attempts to gen-erate EXC resins based on CyMe4BTBP and CyMe(4)BTPhen. Previously reported resins all rely on complex synthesis for the formation of a covalent bond between extractant and support by contrast with the sim-pler solvent impregnation method reported here. The Amberchrom supported CyMe4BTBP resin achieved a weight distribution ration (D-Am) of 170 within 60 min and a decontamination factor (DF) of > 10 0 0 for americium over lanthanides by column chromatography. The Amberchrom CyMe(4)BTPhen resin achieved a D-Am of 540 within 30 min and a DF for americium from lanthanides of 60-160. (c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Preparation and application of urea-based derivatized beta-cyclodextrin chiral stationary phase based on diazotized silica microspheres

    He, XiangqiongAhmed, AdeelGuo, ShuaibingKang, Chuankui...
    10页
    查看更多>>摘要：Recently, the design and development of efficient chiral stationary phases is still the core and goal of chiral chromatography. In order to quickly separate chiral drugs, we designed and prepared an environmentally friendly small particle chiral stationary phase: p-methylphenylurea-beta-cyclodextrin chiral stationary phase (SiO2 @PMPU-beta-CD). Firstly, p-methylphenylurea-beta-cyclodextrin (PMPU-beta-CD) was connected to the surface of mesoporous silica microspheres by diazoresin (DR) to prepare a SiO2 @PMPU-beta-CD. In reverse elution mode, the column temperature was set at 25 degrees C, the flow rate was 0.2 mL/min, and ACN-H2O (v/v = 70:30) was used as the elution condition of the mobile phase. The enantiomers of chlorpheniramine maleate, 2-phenylcyclohexanone, and promethazine were separated within 5 min. In addition, the addition of TEAA buffer to the mobile phase improved the enantiomer resolution of chlorpheniramine maleate from 1.03 to 5.69. The experimental results show that the SiO2 @PMPU-beta-CD column can be used for the separation of appellant chiral drugs with good repeatability, and the use of DR instead of silane coupling agent has the advantages of being non-toxic, environmentally protected, and easy to operate, which is of great significance for the development of chiral stationary phase. (C) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Online biological sample preparation with restricted access hybrid carbon nanotubes for determination of anti-smoking drugs

    de Faria, Henrique DipeSilveira, Alberto Thalisondo Prado, Beatriz CarvalhoMoreira Nacif, Julia Louise...
    14页
    查看更多>>摘要：Untreated samples were injected directly into a column switching system, an online SPE technique, using an extraction column packed with restricted access hybrid carbon nanotubes (RAHCNTs), a novel type of restricted access material, in an ultra-high performance liquid chromatography, coupled to a mass spectrometer (UHPLC-MS/MS). The synthesis of used restricted access material was relatively simple, quick, and reproducible, and had a high material yield. Compared to its predecessor, which is covered with bovine serum albumin (Restricted Access Carbon Nanotubes-RACNTs), RAHCNTs have improved performance when used for the analysis of organic compounds. These molecules have a greater adsorption capacity due to the insertion of hydrophilic monomers (tetraethyl orthosilicate (TEOS), 3(trimethoxysilyl)propyl methacrylate (MPS), glycerol dimethacrylate (GDMA), and hydroxyethyl methacrylate (HEMA)) in the external layer. In addition, the formation of the hybrid material provides greater chemical and thermal stability, supporting wide pH and temperature ranges, and high concentrations of acidic and basic solutions. It also supports high proportions of organic solvents in the medium. Another significant advantage of the material is its longer lifetime, as it can be reused for approximately 500 analytical cycles without any loss of efficiency, versus 300 for RACNTs. In the method developed to determine anti-smoking drugs (varenicline and bupropion) simultaneously, as well as nicotine and some of their metabolites in human blood serum, the RAHCNTs were capable of retaining the analytes efficiently, whereas the macromolecules were excluded (almost 100%). The method was linear for all the determined analytes (coefficients of determination higher than 0.99), with limits of detection and quantification ranging from 0.6 to 2.5 mu g L-1 and from 1.0 to 5.0 mu g L-1, respectively. High extraction recovery values were obtained (higher than 88%), as well as inter and intra-assay accuracy and precision results that are in accordance with values recommended by the FDA. The method is promising for therapeutic monitoring and new personalized strategies for patients under antismoking treatment, using a small sample volume (100 mu L). In addition, RAHCNTs are capable of simultaneously extracting analytes with very different physical-chemical characteristics. (c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Optimization of gradient reversed phase high performance liquid chromatography analysis of acetaminophen oxidation metabolites using linear and non-linear retention model

    Vanova, JanaMalinak, DavidAndrys, RudolfKubat, Miroslav...
    11页
    查看更多>>摘要：Acetaminophen (paracetamol, APAP) is one of the most widely used drugs worldwide. Unfortunately, its overdose, which is caused by predominant oxidation of APAP, can lead to acute liver injury. In liver, oxidized APAP is conjugated with glutathione, leading to APAP-glutathione conjugate, which is metabolized to APAP-cysteine and APAP-N-acetylcysteine conjugates. Thus, all of those compounds could be used to monitor APAP metabolism in the overdosed patients. To date, only a limited number of rapid and accurate methods have been reported for the assessment of APAP oxidation metabolites using simple instrumentation, and thus this work was aimed at developing a fast and convenient gradient HPLC-UV/MS method. For this purpose, APAP conjugates with glutathione, cysteine, and N-acetylcysteine were synthesized, purified by preparative liquid chromatography, and characterized by NMR and high-resolution mass spectrometry. The gradient elution conditions were optimized using the window diagram approach and the effects of mobile phase composition and additives on separation and detection sensitivity were evaluated using two, i.e., linear and non-linear isocratic retention models. Quantitative parameters of the developed method were evaluated and the effectiveness, sensitivity, and specificity of the method were demonstrated on the analysis of human kidney HK-2 cell lysates, confirming the suitability of the method for routine use in studies on APAP toxicity.(c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Separation performance of pentiptycene-functionalized triblock copolymers towards the isomers of xylenes, phenols and anilines and the complex components in essential oil

    Duan, RuijuanQi, Meiling
    11页
    查看更多>>摘要：This work presents the investigation of two new pentiptycene (PP)-functionalized triblock copolymers (PEPE1, PEPE2) for gas chromatographic (GC) analyses with an aim to address the separation problems to-ward analytes of high resemblance in properties and a wide variety of components in complex samples. Up to date, these two materials are not reported in any fields. The PEPE1 and PEPE2 columns showed close column efficiency (above 40 0 0 plates/m) but differed in polarity, morphology and separation per-formance. As testified by the challenging Grob test mixture, the PEPE1 column exhibited comprehensively higher separation capability than the PEPE2 column and the commercial reference columns. Also, the PEPE1 column achieved high-resolution performance for both apolar and polar isomers of high resem-blance, such as xylenes, phenols and anilines. Moreover, it displayed high inertness towards carboxylic acids and excellent separation repeatability and reproducibility tested by the aniline isomers with the RSD values in the range of 0.01-0.04% for run-to-run, 0.09-0.13% for day-to-day and 1.2-2.0% for column-to-column, respectively. Its application to GC-MS analysis of the essential oil from tea flowers demonstrated its advantageous separation performance towards a wide range of components and proved its feasibility for practical analyses of complex samples.(c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Adsorption of trichloroethylene on common indoor materials studied using a combined inverse gas chromatography and frequency response technique

    Xie, ShuaiSuuberg, Eric
    9页
    查看更多>>摘要：Building materials can act as sinks and sources of volatile organic compounds (VOCs) which are indoor air contaminants. A knowledge of the dynamics of VOC sorption processes on building materials is needed in order to fully understand how these compounds can influence indoor air quality, and thus, their potential for influencing human health. In the current work, a combination of classical inverse gas chromatography (IGC) and frequency response (FR) technique was used to investigate the sorptive partition and diffusion coefficients of trichloroethylene (TCE) on building materials. This is a compound of considerable interest in many indoor air environments, particularly those impacted by vapor intrusion processes, and the TCE also serves as a model VOC for demonstrating the method. Six typical indoor materials (carpet, cotton, cinderblock, printer paper, polyethylene, drywall) were selected to demonstrate the technique. A selected building material was packed into a stainless-steel column and exposed to a low-concentration TCE flow applied in a sinusoidal temporal pattern at room temperature (22 degrees C). In this case, cinderblock showed the highest sorption uptakes (6209 ng TCE/g material-ppbv TCE) and the slowest sorption rates (7.3 x 10(-10) m(2)/s) among tested materials. The results from the FR-IGC method are compared to other conventionally obtained results and agree well. (c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier