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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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    Melamine sponge functionalized with carbon nanodots for the extraction of polyaromatic hydrocarbons and musks from environmental samples prior to their determination by gas chromatography-mass spectrometry

    Veneti G.Chatzimitakos T.Stalikas C.
    5页
    查看更多>>摘要:? 2022In this study, the functionalization of melamine sponge (MeS) with graphene quantum dots (GQDs) and its use as a sorbent for the extraction of polycyclic aromatic hydrocarbons (PAHs) and musks from environmental samples are presented. The MeS@GQDs is prepared by modification of the MeS with GQDs in a one-pot, single-step, in situ synthesis, using citric acid as carbon source. The produced MeS@GQDs was used to develop and optimize an analytical method based on solid-phase extraction mode, for the subsequent analysis of soil samples and treated effluents exploiting the extraction properties of the synthesized MeS@GQDs. The developed method not only presented satisfactory repeatability (RSD<8.7%) and inter-day repeatability (RSD<9.6%), but also its limits of quantification were found to be low (15-80 ng L?1). Moreover, the proposed method was linear in a wide range of concentrations (0.015-11.8 μg L?1) and the recoveries from difficult matrixes, such as treated effluents and soil, were satisfactory. Overall, the use of the sorbent for the development of a new analytical method was found to be advantageous as compared with other reported methods.

    Topology optimization based deterministic lateral displacement array design for cell separation

    Tang H.Niu J.Jin H.Lin S....
    5页
    查看更多>>摘要:? 2022Circulating tumor cell (CTC) can be used to guide cancer theranostics. How to isolate efficiently CTCs from blood owns great clinical requirement. Deterministic lateral displacement (DLD) is a pillar-array-based effective passive microfluidic method to separate cells based on their sizes. DLD is a potential CTC isolation tool. Pillar shape is one of the key priorities in DLD array design. Altered zigzag mode is a normally undesired phenomenon that leads zigzag particles away from flow direction. This work makes use of the altered zigzag mode to manipulate zigzag particles for the first time, and developed a novel DLD chip with topology optimized pillar shape and a wide DLD channel. The novel designing method based on topology optimization (TO) greatly increases lateral displacement of different sized cells, meanwhile demonstrates its universality and expansibility. The proposed structure has the ability to shorten the device and to manipulate cells flexibly. Bead experiment has been applied to determine the critical diameter of the DLD array. Numerical, bead and cell experiment have been carried out to verify the separation efficiency of the structure. The TO-based wide DLD channel promotes the separation efficiency.

    Recycling gradient-elution liquid chromatography for the analysis of chemical-composition distributions of polymers

    Niezen L.E.Pirok B.W.J.Schoenmakers P.J.Somsen G.W....
    5页
    查看更多>>摘要:? 2022Synthetic polymers typically show dispersity in molecular weight and potentially in chemical composition. For the analysis of the chemical-composition distribution (CCD) gradient liquid chromatography may be used. The CCD obtained using this method is often convoluted with an underlying molecular-weight distribution (MWD). In this paper we demonstrate that the influence of the MWD can be reduced using very steep gradients and that such gradients are best realized utilizing recycling gradient liquid chromatography (LC?LC). This method allows for a more-accurate determination of the CCD and the assessment of (approximate) critical conditions (if these exist), even when high-molecular-weight standards of narrow dispersity are not readily available. The performance and usefulness of the approach is demonstrated for several polystyrene standards, and for the separation of statistical copolymers consisting of styrene/methyl methacrylate and methyl methacrylate/butyl methacrylate. For the latter case, approximate critical compositions of the copolymers were calculated from the critical compositions of two homopolymers and one copolymer of known chemical composition, allowing for a determination of the CCD of unknown samples. Using this approach it is shown that the copolymers elute significantly closer to the predicted critical compositions after recycling of the gradient. This is most clear for the lowest-molecular-weight copolymer (Mw = 4.2 kDa), for which the difference between measured and predicted elution composition decreases from 7.9% without recycling to 1.4% after recycling.

    One-step salting-out extraction of bacteriophage from its infection broth of Acinetobacter baumannii

    Duan S.Dong Y.Xu Y.Xiu Z....
    5页
    查看更多>>摘要:? 2022Phages as a potential alternative antibiotic for multidrug-resistant bacterial infections are receiving great attention worldwide. However, the traditional separation and purification of phage are cumbersome, time-consuming, costly and inefficient. In this study, phage phiAB9 for multidrug-resistant Acinetobacter baumannii was separated and purified by a simple and cost-saving one-step salting-out extraction (SOE). Several kinds of salts and organic solvents without effect on phage survival were chosen to form the SOE systems, and the composition of SOE systems were optimized according to the phage recovery rate and impurity removal rate. After one-step SOE by an optimal system composed of 18% (w/w) ammonium citrate and 40% (w/w) ethyl acetate, the recovery rate of phage in the middle phase could reach to 90.82%, and most proteins (99.57%), cells (97.98%) and endotoxin (84.08%) were well removed, with a concentration factor of 210 and the purification factors of phage to proteins, cells and endotoxin were 303.64, 133.55 and 5.36, respectively. Comparing with two-step SOE and traditional aqueous two-phase extraction, one-step SOE may be an available method for the separation and purification of phages.

    Determination of polycyclic aromatic hydrocarbons in surface waters by high performance liquid chromatography previous to preconcentration through solid-phase extraction by using polymeric monoliths

    Critto E.F.Medina G.Reta M.Acquaviva A....
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.A simple, sensitive and reproducible solid-phase extraction method using plastic cartridges containing a monolithic sorbent (m-SPE), coupled to reverse phase liquid chromatography analysis, aiming to determine fifteen polycyclic aromatic hydrocarbons in surface water samples, was developed. The sorbent was easily prepared through a thermal polymerization reaction by using a mixture of n-butyl methacrylate as non-polar monomer and ethylene glycol dimethacrylate as crosslinker contained in a typical Polypropylene syringe cartridge. The effect of different parameters (type of hydrophobic monomer, elution solvent, sample volume, sorbent amount and sorbent load capacity) on the extraction efficiency was optimized. The optimal conditions were achieved by using n-butyl methacrylate as monomer, tetrahydrofurane (THF) as solvent for sorbent cleaning, THF:acetone (1:1) as elution solvent, 25.00 mL of sample volume, 600 μL of the polymerization mixture and 60 μg L?1 as sample loading capacity. Finally, the sorbent charge capacity, the reusability of the cartridges and the extraction efficiency of the m-SPE monolith, as compared with a typical C8 cartridge, were evaluated. Under the optimized experimental conditions, enrichment factors were between 76 and 103, relative recovery factors from 78 to 103%, accuracy values in the range of 58 to 98%, and inter-batch reproducibility values from between 2 and 10%, were obtained. The limits of detection and quantification were obtained by two different procedures: the signal to noise (S/N) ratios (3 and 10, respectively) and the IUPAC convention. The lowest LOD and LOQ values, obtained with the S/N ratios, were between 0.02 and 1.00 μg L?1, respectively whereas with the IUPAC convention the values were between 0.07 and 5 μg L?1. Using this procedure, several PAHs could be detected in the surface water sample taken from a river stream located in La Plata city (Buenos Aires Province, Argentina).

    Retention index based approach for simulation of results and application for validation of compound identification in comprehensive two-dimensional gas chromatography

    Kakanopas P.Janta P.Hermatasia F.Kulsing C....
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.In this work, first and second dimensional retention index (1I and 2I) based calculation approach is established to simulate peak retention times (1tR and 2tR) of samples for the given sets of volatile compounds in comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS). For the result without 1tR and 2tR data of alkane references (1tR(n) and 2tR(n)), the following steps were applied: (1) curve fitting based on van den Dool and Kratz relationship in order to simulate 1tR(n) using a training set of volatile compounds in a sample with their experimental 1tR data, and (2) simulation of 2tR(n) at different 1tR(n) to construct their isovolatility curves based on a nonlinear equation with p1-p5 parameters and a constant (within the ranges of -0.0052 to 0.0049, -0.6181 to -0.0230, -26.4775 to -0.2698, 0.0050 to 9.6259, -7.2976 to -3.9524 and 0.9157 to 4.0779, respectively). These parameters were obtained by performing curve fitting according to the experimental 2tR data of the same training set with the least square values ranging from 4.58×10?15 to 32.55. Simulation of 1tR and 2tR of target analytes (1tR,sim and 2tR,sim) with known 1I and 2I were performed using 1tR(n) and the simulated isovolatility curves. All the calculations and curve fittings were carried out by using Solver in Microsoft Excel. The approach was applied to simulate results for 542 compounds in several samples including analysis of saffron (Crocus sativas L.), Boswellia papyrifera, acacia honey and incense powder/smoke, perfume and cannabis either reported from literature or from the experiments in this work using different experimental approaches. These were compared with the experimental data showing correlation with the R2 ranges of 0.98–1.00 and 0.80–0.97 for 1tR and 2tR, respectively. This approach was then applied to propose 6 compounds which may be incorrectly identified based on the differences of >2 times of the standard deviations between 2tR,sim and the experimental 2tR in both residue and leave-one-out analyses.

    Modeling of the transient diffusion regime in fully porous particles—Application to the analysis of large biomolecules by ultra-high pressure liquid chromatography

    Gritti F.
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.The transient diffusion regime of large biomolecules such as monoclonal antibodies, double-stranded (ds) DNA (base pair number ~ 100), and virus-like particles is modeled in a single fully porous particle utilized as size exclusion chromatography (SEC) packing materials in ultra-high pressure liquid chromatography (UHPLC). The expression of the time and space dependent concentration profiles is derived for a step concentration change. Four different UHPLC particles were considered in the calculations depending on the size of the analyte : 2.0 μm 125 ? Bridge-Ethylene-Hybrid (BEH) XBridgeTM particles for small molecules (size: 4 ?), 2.0 μm 125 ? and 250 ? BEH particles for monoclonal antibodies (size: 55 ?), 2.0 μm 250 ? and 2.5 μm 450 ? BEH particles for dsDNA (size: 160 ?), and 2.5 μm 900 ? BEH particles for virus-like particles (size: 500 ?). The accessible porosities and the hindrance diffusion factors of these analytes were determined from the physical reconstruction of the internal structure of a 2.0 μm 130 ? BEH particle and from the simulation of the analyte mobility in the reconstructed mesopores. The analysis of the transient diffusion profiles reveals that there is insufficient time for the largest analytes to fully equilibrate the BEH particles in UHPLC. The dynamic capacity of the BEH particles is estimated to decrease from more than 99% for small molecules to 96% for monoclonal antibodies, 74% for 100 base pair dsDNA, and to less than 2% for virus-like particles. A full but reduced column capacity relative to fully porous particles can be recovered for monoclonal antibodies by considering superficially porous particles with a core-to-particle diameter ratio of about 0.8. In contrast, this is not possible for either large dsDNA (base pair number ≥ 100) or virus-like particles because the shell thickness would become smaller than the mesopore size required. The presented results open up two research avenues in order to analyze such large biomolecules by UHPLC: prepare ultra-high pressure-resistant sub-3 μm silica-based particles with pore sizes much larger than 1000 ? and design proper nonporous macrostructures to load, trap, separate, and elute rapidly by gradient UHPLC.

    Adsorption properties and gas chromatographic application of a composite surface-layer sorbent with Terephthalic acid-based metal-organic framework

    Onuchak L.A.Kopytin K.A.Kuraeva Y.G.Pariichuk M.Y....
    5页
    查看更多>>摘要:? 2022In this paper, we report on the fabrication of a new material SiO2@MIL-101(Cr), which synthesis is based on the metal-organic framework MIL-101(Cr) and the silica support Chromosorb W. The obtained surface-layer sorbent was analyzed by powder X-ray diffraction analysis, Raman spectroscopy and porosity measurement. The retention regularities and the thermodynamic characteristics of the sorption of volatile organic compounds from the gas phase were studied for the packed column with the surface-layer sorbent SiO2@MIL-101(Cr). The results indicated that the adsorbent-adsorbate interaction in the mesoporous structure of SiO2@MIL-101(Cr) depends not only on the dispersion attractive forces but also on π-π-stacking and specific interactions with hydroxyl groups and metal cations’ open coordination sites on the pore surface. In this work, we gave examples of gas chromatograms of isomers of alkanes, arenes, and chlorine derivatives of methane on a packed column with the obtained sorbent. Examples of gas chromatograms of isomers of alkanes, arenes, and chlorine derivatives of methane on a packed column with the obtained sorbent are presented.

    Bayesian optimization using multiple directional objective functions allows the rapid inverse fitting of parameters for chromatography simulations

    Japel R.C.Buyel J.F.
    5页
    查看更多>>摘要:? 2022 The AuthorsThe modeling of chromatographic separations can speed up downstream process development, reducing the time to market and corresponding development costs for new products such as pharmaceuticals. However, calibrating such models by identifying suitable parameter values for mass transport and sorption is a major, time-consuming challenge that can hinder model development and improvement. We therefore designed a new approach based on Bayesian optimization (BayesOpt) and Gaussian processes that reduced the time required to compute relevant chromatography parameters by up to two orders of magnitude compared to a multistart gradient descent and a genetic algorithm. We compared the three approaches side by side to process several internal and external datasets for ion exchange chromatography (based on a steric mass action isotherm) and hydrophobic interaction chromatography (a modified version of a recently published five-parameter isotherm) as well as different input data types (gradient elution data alone vs gradient elution and breakthrough data). We found that BayesOpt computation was consistently faster than the other approaches when using either single-core or 12-cores computer processing units. The error of the BayesOpt parameter estimates was higher than that of the competing algorithms, but still two orders of magnitude less than the variability of our experimental data, indicating BayesOpts applicability for chromatography modeling. The low computational demand of BayesOpt will facilitate rapid model development and improvement even for large datasets (e.g., > 100 proteins) and increase its suitability for research laboratories or small and medium enterprises lacking access to dedicated mainframe computers.

    2,4-dinitrophenylhydrazine capturing combined with mass defect filtering strategy to identify aliphatic aldehydes in biological samples

    Wang S.-Y.Liu H.Zhu J.-H.Li S.-L....
    5页
    查看更多>>摘要:? 2022 Elsevier B.V.Aliphatic aldehydes are toxic substances that correlate with the onset of many diseases. However, up to date, the methods to identify aliphatic aldehydes in biological samples are less selectivity and/or robustness. In this study, a strategy based on 2,4-dinitrophenylhydrazine (DNPH) capturing combined with mass defect filtering (MDF) was established and validated to identify aliphatic aldehydes in two biological samples (serum of immunosuppressed rats and oxidative damaged cells). Firstly, the mass spectrometric characteristic ions (m/z 163.01, 163.02 and 191.04) and fragmentation pathways of aldehyde-DNPHs were acquired through analyzing the standard references. Then, biological samples were derivatized by DNPH, a routine reagent, and subsequently assessed on an ultra-performance liquid chromatography coupled time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). Thirdly, the raw chromatogram was processed by MDF method to obtain interference-free chromatogram. Fourthly, the aldehyde-DNPHs were characterized through investigating the mass spectrometric information of each peak referred to the identified characteristic ions and fragmentation pathways. Finally, 6 and 8 aliphatic aldehydes were exclusively identified in serum of immunosuppressed rats and supernatant of oxidative damaged cells. Among which, propanal and butanal were positively correlate with immunosuppression, while formalin was more relevant to oxidative stress. The results demonstrated that the established strategy could robustly characterize the aliphatic aldehydes in biological samples, which would be helpful to evaluate the physical conditions of subjects.