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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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    Green methodology based on active air sampling followed by solid phase microextraction and gas chromatography-tandem mass spectrometry analysis to determine hazardous substances in different environments related to tire rubber

    Armada, DanielCeleiro, MariaDagnac, ThierryLlompart, Maria...
    15页
    查看更多>>摘要：A fast, efficient, and simple air sampling methodology was developed to study a high number of volatile and semivolatile organic compounds in air above tire rubber materials and surfaces made of recycled tire rubber. The proposed method, based on active sampling (solid-phase extraction, SPE) using a small quantity of sorbent material (25 mg) followed by solid-phase microextraction (SPME) and gas chromatography-tandem mass spectrometry analysis, was developed with the aim of determining 40 organics substances including polycyclic aromatic hydrocarbons (PAHs), plasticizers, antioxidants, and vulcanization agents. An experimental design was carried out to study the influence of main factors such as type of SPME fibre, solvent addition, headspace volume, stirring, as well as the factor interactions. Method performance showed good linearity in a broad concentration range (0.05 to 200 ng m(-3), for most compounds), with coefficients of determination (R-2 ) higher than 0.9900. Whole method precision (<= 16 %) and accuracy were also satisfactory, obtaining quantitative recoveries (mean values between 80 and 110 % in most cases). Limits of detection and quantification have also been calculated, yielding values of sub ng m(-3) for most compounds. The validated method was applied to outdoor and indoor air environments including playgrounds, football pitches and warehouses showing the presence of most target compounds in the samples achieving high levels for some PAHs (concentrations up to 51 ng m(-3)), benzothiazole (BTZ), diisobutyl- dibutyl-and di-(2-ethylhexyl)-phthalate, among others, reaching concentrations up to hundreds of ng m(-3) (BTZ). This is the first time that the combination of techniques SPE and SPME is applied for these families of chemicals, and it is also the first time that this approach is proposed for the simultaneous multiclass compound extraction of substances of different chemical families. The whole sampling and extraction procedure is performed in a short period of time (61 min) allowing high throughput. The elimination of the use of organic solvents and waste generation by using only 25 mg of sorbent and a SPME fibre than are both reused makes the method sustainable and in consonance with the principles of the green chemistry. The method can be implemented in any routine lab and easily automated using a SPME autosampler. (C) 2022 The Author(s). Published by Elsevier B.V.
      原文链接:
    • NSTL
    • Elsevier

    Inexpensive portable capillary electrophoresis instrument for Monitoring Zinc(II) in remote areas

    Zhang, MinSmejkal, PetrRobertson, Johnathon C.Atia, Mostafa A....
    11页
    查看更多>>摘要：A compact, inexpensive capillary electrophoresis instrument was developed for monitoring metal ions and evaluated for Zn(II) in remote contaminated locations in western Tasmania, Australia. The portable instrument, measuring 21 cm x 10 cm x 7 cm, was powered from the USB port of a laptop computer and built from off-the-shelf components costing similar to$1200 USD. Electrophoretic separations were conducted using a fused silica capillary (10-50 mu m I.D.), applying 8.5 kV over capillaries ranging from 25 cm to 40 cm in length. The capillary inlet was connected with an electrically grounded cross-piece as flow-through injection interface. Automated fluidic management was achieved by controlling four mini peristaltic pumps and a solenoid valve. Detection was realised using a purpose-built visible LED absorption detector, optimised for the detection of Co(II), Cu(II) and Zn(II) after complexation with 4-(2-Pyridylazo) resorcinol (PAR). Limits of detection of sub-mu M were obtained. The instrument was tested for continuous operation in the laboratory for up to 3 months, and relative standard deviations of < 5.4% were found over 945 consecutive injections. In the field, the system was able to measure 106 samples within 11 h, the time it can be powered from the laptop computer. As Field measurement of Zn(II) in western Tasmania was demonstrated to show capability for on-site metal testing. (C) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Are two liquid chromatography columns in tandem better than one?: Answers from the hydrophobic subtraction model

    Liu, ZhiyangFoley, Joe P.
    11页
    查看更多>>摘要：An approach is described for determining if there is an intrinsic advantage, from a selectivity and resolution perspective, of using two different UHPLC/HPLC reversed-phase columns in tandem for a separation of a given sample compared to a single U/HPLC reversed-phase column that provides the same plate number. Retention data for 16 compounds extracted directly from the hydrophobic subtraction model (HSM) database at HPLCColumns.org are used to simulate and then compare the critical resolution of those compounds obtained using HSM conditions (isocratic elution at 35 degrees C using 50% acetonitrile, 50% aqueous phosphate buffer at pH 2.8 or 7) for each of 662 U/HPLC single columns or 218,791 combinations of tandem columns and assuming a modest plate number of 80 0 0. The critical resolution obtained for 16 additional "n-1" samples created by the systematic removal of one of the original 16 compounds was also compared using single-and tandem-column LC, as was the critical resolution obtained for thousands of synthetic samples generated by randomly varying HSM solute descriptors for each synthetic compound. When all possible single-column or tandem-column results were compared, a significant advantage was observed with tandem-column liquid chromatography (TC-LC), with an average increase in critical resolution of 0.63 (pH 2.8) or 0.75 (pH 7) units observed for the synthetic samples with the smallest number of components (m = 5). As the number of components in a sample increased, the average improvement in critical resolution (ARs,crit) using TC-LC gradually decreased from about 0.70 for m = 5 to 0.18 for m = 32 components. The average improvement in critical resolution achieved by switching from SC-LC to TC-LC was also lower when a smaller number of columns and column combinations were available to explore, as would be the case for a finite column inventory in a real laboratory. Nevertheless, on average there does appear to be an intrinsic advantage of tandem-column liquid chromatography, however small, which can be amplified by using high efficiency columns. (C) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Purification of biflavonoids from Selaginelladoe derleinii Hieron by special covalent organic polymers material

    Li, GangGao, XinyuQin, GuifangLei, Jie...
    13页
    查看更多>>摘要：Herein, a novel covalent organic polymers (COP) material based on acylhydrazone bond (AB-COP) was prepared as an efficient extraction material for enriching natural medicine biflavonoids from Selaginella doederleinii Hieron. The obtained AB-COP structure was characterized in detail. And it was the first time to investigate the effect of AB-COP on the adsorption of biflavonoids. The effects of initial concentration of solution, adsorption temperature, solid-liquid ratio, adsorption time on the adsorption of biflavonoids were studied. In addition, adsorption kinetic model, adsorption thermodynamic model and density functional theory (DFT) were also investigated to evaluate the adsorption mechanism. At the same time, the static desorption and reusability of AB-COP were investigated. Finally, the dynamic enrichment effect of AB-COP for biflavonoids was investigated. The results showed that AB-COP was successfully synthesized by Fourier transform infrared spectroscopy (FT-IR), solid state nuclear magnetism (NMR), X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), laser particle size analysis and Brunner Emmet Teller (BET) specific surface area test. The optimized adsorption parameters of AB-COP were initial concentration of 0.5 mg/mL, temperature of 45 degrees C, solid-liquid ratio of 10:10 (mg/mL), adsorption time of 60 min. The Langmuir adsorption isotherm could effectively describe the adsorption process, the pseudo-secondary adsorption model could accurately explain the adsorption mechanism, and the DFT calculations revealed that the interaction forces of AB-COP and biflavonoids were pi-pi stacking and hydrogen bonding. In addition, AB-COP successfully resolved biflavonoids through urea-methanol (1.3 mol/L), and the material can be reused at least four times. Finally, the solid phase extraction (SPE) chromatographic column prepared by AB-COP was successfully applied to the enrichment of biflavonoids from S. doederleinii, and the effect was significantly better than traditional chromatography materials, andthis method was also successfully applied to the enrichment of flavonoids in other plant extracts including Flos sophorae, Pericarpium viride, Lophatheri herba, Herba cuscutae. These results provide references for further purification of bioactive ingredients from plant extracts by using AB-COP. (C) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Preparation and evaluation of ultra-long open-tubular capillary columns modified with zeolitic imidazolate framework-8 incorporated polymeric porous layer for liquid chromatography

    Zhong, ZhihuaZhu, ManmanChu, ZhanyingRen, Xingfa...
    7页
    查看更多>>摘要：An ultra-long (5 m) open tubular capillary liquid chromatographic column was prepared by incorporating Metal Organic Framework (MOF), zeolitic imidazolate framework-8 (ZIF-8), directly into polymer coating, which was synthesized by the copolymerization of 4-vinylbenzyl chloride and divinylbenzene, on the capillary inner surface. The prepared ZIF-8 incorporate polymeric open tubular capillary column (denoted as ZIF-8-p(VBC/DVB) OTCC) was evaluated with thiourea, alkylbenzenes and polycyclic aromatic hydrocarbons as probe molecules. The results showed that the ultra-long column achieved absolute column efficiency of 130,0 0 0 plates for thiourea, and the incorporation of ZIF-8 effectively improved the chromatography performance of the OTCC. Baseline separation of aromatic compounds and position isomers was achieved based on multiple interactions provided by the zeolitic imidazolate framework and polymer, including hydrophobic interaction, pi-pi stacking interaction and the coordination effect. The RSD values (run-to-run, day-to-day, column-to-column, n = 3) of retention time of phenylenediamine isomers and propylbenzene isomers were less than 0.7%, 1.2% and 4.0% respectively, suggesting excellent repeatability. Finally, the prepared ZIF-8-p(VBC/DVB) OTCC was applied to the separation of hydroxyacetophenone isomers with satisfied results. (C) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    50 years of chiral liquid Chromatography. How it started

    Davankov, Vadim A.
    3页
    查看更多>>摘要：The birth of modern chiral liquid chromatography can be traced back to the years 1968-71 when the first complete resolution of a racemic amino acid was obtained and presented in the literature. Extreme enantioselectivity was achieved due to the introduction of ligand exchange principle, i.e. participation of a copper ion in the solute-sorbent interactions. Simultaneously, first microporous (hypercrosslinked) polymeric matrixes were introduced, thus enhancing the chromatographic efficiency of the process. (c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Non-targeted Gas Chromatography Orbitrap Mass Spectrometry qualitative and quantitative analysis of semi-volatile organic compounds in indoor dust using the Regions of Interest Multivariate Curve Resolution chemometrics procedure

    Pourasil, Roudabeh Sadat MoazeniCristale, JoyceLacorte, SilviaTauler, Roma...
    23页
    查看更多>>摘要：In this study, non-targeted gas chromatography-Orbitrap-mass spectrometry (GC-Orbitrap-MS) analysis of semi-volatile organic compounds (SVOCs) in indoor environmental dust samples is proposed. High resolution mass spectrometry (HRMS) provides massive amounts of information-rich mass data which presents storage and processing challenges. Thus, a combination of the regions of interest (ROI) data filtering and mass compression method, together with the multivariate curve resolution-alternating least squares (MCR-ALS) data resolution method (which is called the ROIMCR procedure), is applied to solve huge data analysis challenges. The ROI method assures a significant reduction of the computer storage requirements of mass spectrometry data without any significant loss of spectral resolution nor of accuracy on m/z measures. On the other side, the MCR-ALS method allows the total resolution of the elution and spectral profiles of the different constituents present in the analyzed samples, not requiring their chromatographic peak alignment nor their chromatographic peak shape modelling using natural constraints like non-negativity. Since all the possible species are investigated by the ROIMCR method, it is a powerful tool for non-targeted analysis. In order to check that the sample constituents are correctly recovered and identified by the proposed ROIMCR procedure when is applied to non-targeted GC-Orbitrap-MS analysis, a set of lab-emulated dust samples at different concentration levels were qualitatively and quantitatively analyzed in detail. Then, to evaluate the performance of the proposed ROIMCR procedure, this method was applied to the same type of non-targeted GC-Orbitrap-MS analysis data of two real dust samples with unknown compositions. Many chemical compounds present in the lab-emulated dust samples were correctly identified and quantified in these dust samples. An additional number of extra chemical compounds were resolved in these real dust samples, whose identification as putative constituents of these samples is proposed. The ROIMCR procedure proposed in this work facilitates the simultaneous data processing of complex analytical samples and allows the detection and identification of possible extra sample constituents. As a final conclusion of this work, the combination of the GC-Orbitrap-MS and ROIMCR methods, is shown to be a reliable tool for the non-targeted qualitative and quantitative analysis of complex analytical and environmental samples. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )
      原文链接:
    • NSTL
    • Elsevier

    Evaluation of hydrophobic charge-induction ligand efficiency for protein adsorption in one single cycle

    Kong, XinyaFu, JiaxueZhang, SiqiLi, Kaibin...
    12页
    查看更多>>摘要：Ligand is an essential part of the cost of adsorbent preparation, which needs to be carefully selected and evaluated. In this paper, we introduced ligand efficiency (L-e) with three levels (recovery, preparation and cost) to form a selection strategy for evaluation of the efficiency of hydrophobic charge-induction ligand. These functions were calculated from static/dynamic binding capacity, desorption efficiency, coupling efficiency and ligand cost. Nine kinds of ligand were used to demonstrate this strategy. The coupling efficiency was determined by preparing the adsorbents with different kinds and densities of ligand. These adsorbents were characterized by FT-IR, SEM. Then adsorption equilibrium, adsorption kinetics, and frontal adsorption experiments were used to test the adsorption and desorption performance of these adsorbents. Finally, L(e)s of recovery, preparation and cost were calculated. The results showed there were apparent differences in L(e)s between ligand types and densities under static and dynamic adsorption conditions. 4FF-Tryptophan with 52 mu mol/g adsorbent had the best performance with the lowest static/dynamic L-e of recovery, preparation and ligand cost. Compared with those methods evaluated by static saturated adsorption capacity or dynamic binding capacity at 10% breakthrough, the selection strategy based on ligand efficiency is more suitable for subsequent research and industrial amplification. (C) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Extraction of fucoxanthin from Chaetoceros calcitrans by electropermeabilization-assisted liquid biphasic flotation system

    Khoo, Kuan ShiongOoi, Chien WeiChew, Kit WayneChia, Shir Reen...
    11页
    查看更多>>摘要：Electropermeabilization-assisted liquid biphasic flotation (LBF) system is an emerging extraction system facilitated by the adsorptive bubble separation and the electroporation in an aqueous two-phase medium. This integrative extraction system is well suited for the direct recovery of intracellular biocompounds from cells without the needs of discrete steps of mid-or down-stream bioprocessing. The potential of electropermeabilization-assisted LBF system in bioseparation was demonstrated in this study by using the diatom Chaetoceros calcitrans ( C. calcitrans) as the source of fucoxanthin, which is a promising an-tioxidant highly demanded by food and pharmaceutical industries. The extraction performances of LBF and electropermeabilization-assisted LBF system were comprehensively evaluated under the optimal op-erating conditions. Comparatively, the optimized LBF and electropermeabilization-assisted LBF systems achieved the satisfactory yields of fucoxanthin, i.e., 14.78 mg/g and 16.09 mg/g, respectively. The good recovery of fucoxanthin using electropermeabilization-assisted LBF system could be attributed to the higher release of fucoxanthin from the electrotreated C. calcitrans, allowing a higher partition of fucox-anthin to the top phase of LBF system (236.72 as compared to 152.15 from LBF system). In addition, the fucoxanthin extracted suing both methods exhibit satisfactory antioxidant activities. The application of electropermeabilization-assisted LBF system in the extraction of fucoxanthin is a greener and highly ef-ficient bioprocessing route which can be prospectively extended to other biocompound extraction from microalgal sources. (c) 2022 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Improving retention-time prediction in supercritical-fluid chromatography by multivariate modelling

    Molenaar, Stef R. A.Savova, Mariyana, VCross, RebeccaFerguson, Paul D....
    9页
    查看更多>>摘要：The prediction of chromatographic retention under supercritical-fluid chromatography (SFC) conditions was studied, using established and novel theoretical models over ranges of modifier content, pressure and temperature. Whereas retention models used for liquid chromatography often only consider the modifier fraction, retention in SFC depends much more strongly on pressure and temperature. The viability of combining several retention models into surfaces that describe the effects of both modifier fraction and pressure was investigated. The ability of commonly used retention models to describe retention as a function of modifier fraction, expressed either as mass or volume fraction, pressure and density was assessed. Using the multivariate surfaces, retention-time prediction for isocratic separations at constant temperature improved significantly compared to univariate modelling when both pressure and modifier fractions were changed. The "mixed-mode" model with an additional exponential pressure or density parameter was able to predict retention times within 5%, with the majority of the predictions within 2%. The use of mass fraction and density further improves retention modelling compared to volume fraction and pressure. These variables however, do require extra computations. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )
      原文链接:
    • NSTL
    • Elsevier