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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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    A strategy to process hundred-gram level complex sample using liquid-liquid-refining extraction and consecutive counter-current chromatography: Toona sinensis case study

    Yang, YiGuo, ShuangGu, Dongyu
    7页
    查看更多>>摘要：Large-scale preparation of target compounds from complex samples is facing great challenges. In the present study, an efficient strategy for large-scale preparation of target compound was proposed and successfully applied in the separation of active components from Toona sinensis. The pretreatment technology of liquid-liquid refining extraction (LLRE) combined with consecutive high-speed counter-current chromatography (HSCCC) was used to process hundred grams of extractions. Firstly, two phase solvent systems composed of n-hexane-ethyl acetate-methanol-water (5:5:5:5, v/v) and (2:5:2:5, v/v) were used to remove low polar and high polar impurities from 100 g crude extracts of T. sinensis, respectively, and 9.25 g of crude sample was obtained. And then, n-hexane-ethyl acetate-methanol-water (2.5:5:2.5:5, v/v) was used as the solvent system for HSCCC separation. The isocratic elution mode with max loading and consecutive injections mode were investigated to obtain more target compound. As a result, ethyl gallate with purity of 97% was successfully separated by 5 times consecutive counter-current chromatography. The separation was repeated once. Finally, ethyl gallate (3.73 g) was isolated from 9.25 g of crude sample (100 g crude extracts). The results demonstrated that the yield increased from 0.26 g/h/L of untreated crude extract to 0.93 g/h/L of LLRE pre-treated sample for single injection, and further increased to 1.62 g/h/L for 5 consecutive injections mode with the present method. (c) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Applications of covalent organic frameworks and their composites in the extraction of pesticides from different samples

    Bagheri, Ahmad RezaAramesh, NahalHaddad, Paul R.
    17页
    查看更多>>摘要：Pesticides are used extensively in a wide range of applications and due to their high rate of consumption, they are ubiquitous in the different media and samples like environment, water sources, air, soil, biological materials, wastes (liquids, solids or sludges), vegetables and fruits, where they can persist for long periods. Pesticides often have hazardous side effects and can cause a range of harmful diseases like Parkinson, Alzheimer, asthma, depression and anxiety, cancer, etc, even at low concentrations. To this end, extraction, pre-concentration and determination of pesticides from various samples presents significant challenges caused by sample complexity and the low concentrations of them in many samples. Often, direct extraction and determination of pesticides are impossible due to their low concentrations and the complexity of samples. The main goals of sample preparation are removing interfering species, pre-concentrating target analyte/s and converting the analytes into more stable forms (when needed). The most popular approach is solid-phase extraction due to its simplicity, efficiency, ease of operation and low cost. This method is based on using a wide variety of materials, among which covalent organic frameworks (COFs) can be identified as an emerging class of highly versatile materials exhibiting advantageous properties, such as a porous and crystalline structure, pre-designable structure, high physical and chemical stability, ease of modification, high surface area and high adsorption capacity. The present review will cover recent developments in synthesis and applications of COFs and their composites for extraction of pesticides, different synthesis approaches of COFs, possible mechanisms for interaction of COFs-based adsorbents with pesticides and finally, future prospects and challenges in the fabrication and utilization of COFs and their composites for extraction of pesticides. (c) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Comparison of chromatographic performance of co-grafted silica using octadecene respectively with vinylpyrrolidone, vinylimidazole and vinylpyridine

    Quan, KaijunChen, JiaQiu, HongdengFan, Chao...
    9页
    查看更多>>摘要：Three reversed-phase liquid chromatography (RPLC) stationary phases were obtained by using long-chain 1-octadecene (OD) co-grafted with three short-chain monomers, including N-vinylpyrrolidone (NVP), 1-vinylimidazole (VIm) and 4-vinylpyridine (VPy), respectively (noted as Sil@ODNVP, Sil@ODVIm and Sil@ODVPy). Peak broadening phenomenon in RPLC mode which resulted by short-chain was examined carefully. Compared with Sil@ODNVP, both of Sil@ODVIm and Sil@ODVPy had smaller peak width and higher column efficiency in the separation of 10 polycyclic aromatic hydrocarbons (PAHs), 7 alkyl benzenes, 7 aromatic acids, 7 aromatic esters and 9 phenols. In addition, VPy has the strongest ion exchange capacity than other two short-chains. In this case, we can see that VPy and VIm maybe more suitable to be used as functional monomeric modifiers of new chromatographic stationary phases. (c) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Combination of zeolitic imidazolate framework-67 and magnetic porous porphyrin organic polymer for preconcentration of neonicotinoid insecticides in river water

    Selahle, Shirley KholofeloMpupa, AneleNomngongo, Philiswa Nosizo
    12页
    查看更多>>摘要：A nanostructured material composed of zeolitic imidazolate framework-67 and magnetic porous porphyrin organic polymer (ZIF-67@MPPOP) was successfully synthesized and applied for the enrichment of neonicotinoid insecticides in river water. The analytes were detected and quantified using high performance liquid chromatography coupled with diode array detector (HPLC-DAD) and liquid chromatography mass spectrometry (LC-MS). Influential experimental parameters were optimized using response surface methodology based on Box Behnken design. The adsorption capacities were 69.46, 80.53, 85.39 and 90.0 mg g(-1) for thiamethoxam, imidacloprid, acetamiprid and clothianidin, respectively. At optimal experimental conditions, low limit of detection (LOD), limit of quantification (LOQ) and linearity were 0.0091-0.04 mu g L-1, 0.04-0.13 mu g L-1 and (0.04-600 mu g L-1), respectively. The relative standard deviation used to evaluate the reproducibility and repeatability of the method was less than 5%. Finally, the method was employed for determination of four neonicotinoid insecticides in river water. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Hypercrosslinked polymer microspheres decorated with anion- and cation-exchange groups for the simultaneous solid-phase extraction of acidic and basic analytes from environmental waters

    Carles Nadal, JoanDargo, StuartBorrull, FrancescCormack, Peter A. G....
    13页
    查看更多>>摘要：Mixed-mode ion-exchange sorbents were introduced to improve the selectivity and retention of solid-phase extraction (SPE) sorbents. Mixed-mode ion-exchange sorbents integrate reversed-phase chemistry with ion-exchange groups to promote favourable interactions with ionic species. Nevertheless, a need to extract analytes with acidic and basic properties simultaneously within the same SPE cartridge led to the introduction of novel amphoteric/zwitterionic sorbents, which incorporate cation- and anion-exchange moieties within the same functional group attached to the polymeric network. In the present study, the development, preparation and SPE evaluation of two novel hypercrosslinked zwitterionic polymeric sorbents, functionalised with either strong anion-exchange (SAX) and weak cation-exchange (WCX) or weak anion-exchange (WAX) and strong cation-exchange (SCX) groups (namely HXLPP-SAX/WCX and the HXLPP-WAX/SCX), is presented for the simultaneous retention of acidic and basic compounds. The sorbents were prepared by a precipitation polymerisation route which yielded poly(divinylbenzene-co-vinylbenzylchloride) as a precursor polymer; subsequently, the precursor polymer was hypercrosslinked, to increase the specific surface areas and capacities of the sorbents, and then functionalised to impart the zwitterionic character. The HXLPP-SAX/WCX sorbent was decorated with quaternised sarcosine groups and the HXLPP-WAX/SCX sorbent was decorated with taurine moieties. The SPE parameters were optimised to exploit the ionic interactions between compounds and the functional groups. The optimal conditions involve a washing step to remove the compounds retained by hydrophobic interactions, thus increasing the selectivity. The optimised SPE protocol used the quaternised sarcosine-based sorbent followed by liquid chromatography and tandem mass spectrometry, and was applied to determine compounds with acidic and basic properties from environmental samples, such as river water and effluent wastewater samples, with excellent selectivity and matrix effect values below -30% and apparent recovery results ranging from 52% to 105% for most of the compounds. The analytical method was validated for environmental water samples and used in the analysis of samples in which some of the target compounds were found at ng L-1 concentration levels. Crown Copyright (C) 2021 Published by Elsevier B.V.
      原文链接:
    • NSTL
    • Elsevier

    Sensitive determination of illicit drugs in wastewater using enrichment bag-based liquid-phase microextraction and liquid-chromatography tandem mass spectrometry

    Wu, ShifanShen, XiantaoXiang, PingHuang, Chuixiu...
    10页
    查看更多>>摘要：A B S T R A C T To concentrate trace level of analytes in complex wastewater, sample preparation is necessary prior to instrumental analysis. In this work, an enrichment bag-based liquid-phase microextraction (EB-LPME) system was therefore proposed for the first time to isolate and enrich the illicit drugs (am-phetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), ketamine, codeine and fentanyl) from wastewater. Under the optimum EB-LPME conditions, the recoveries of the model illicit drugs were 40-93% with enrichment factors up to 93. The optimized EB-LPME was compared to hollow fiber-LPME (HF-LPME) in terms of the thickness of the supported liquid membrane (SLM), the effective SLM area, extraction recovery and mass transfer flux. Compared with HF-LPME, EB-LPME possesses larger effective SLM area, and provided higher extraction recovery. In addition, EB-LPME provided larger mass transfer flux than HF-LPME, which was mainly due to the differences in SLM thickness. Therefore, SLM thickness was identified as the main mass transfer flux-determining factor experimentally. The matrix ef-fect of EB-LPME was evaluated using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and excellent sample clean-up was confirmed. Subsequently, EB-LPME-LC-MS/MS was validated with satisfac-tory results, and the detection of limit of the proposed method was in the range of 0.3-8.7 ng/L. Finally, with standard addition method, EB-LPME-LC-MS/MS was successfully applied for the determination of the model drugs in a local hospital wastewater from Wuhan, China. This study clearly showed that EB-LPME displayed great potential as an efficient sample preparation method for isolation and enrichment of the drugs/pollutants from complex environmental samples for wastewater-based epidemiology in the near future. (c) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Rapid screening of chemical warfare agents (nerve agents) using dimethyl methylphosphonate as simulant substances in beverages by hollow fiber membrane-protected solid phase microextraction followed by corona discharge ion mobility spectrometry

    Asadi, SajadMaddah, Bozorgmehr
    7页
    查看更多>>摘要：The following work presents a new, rapid, potential to be portable, convenient, and low-cost method using hollow fiber membrane-protected solid phase microextraction followed by corona discharge ion mobility spectrometry which was used for determining dimethyl methylphosphonate in beverages. Response surface methodology based on the design of Box-Behnken was implemented for optimizing the different factors influencing the proposed method for obtaining the best results. Optimal extractions were calculated with 65 mu m polydimethylsiloxane-divinylbenzene fiber, fiber equilibration time of 10 min, stirring rate of the sample solution at 750 rpm, and extraction temperature of 50 degrees C. The proposed technique provided linear range (0.5-50 mu g mL(-1)), good linearity (>0.991), and repeatability (the relative standard deviations of 5.42% and 8.37% of intra- and inter-day analyses, respectively) under the optimized extraction conditions. Finally, the developed method was successfully used for determining dimethyl methylphosphonate in beverages such as coffee mix, fruit juice, tap water, milk, and tea. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier