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Journal of Chromatography. A

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https://www.readbyqxmd.com/read/30442472/metal-organic-frameworks-derived-magnetic-nanoporous-carbon-for-preconcentration-of-organophosphorus-pesticides-from-fruit-samples-followed-by-gas-chromatography-flame-photometric-detection
#1
Dandan Li, Man He, Beibei Chen, Bin Hu
In this work, magnetic nanoporous carbons (MNPCs) based on Zn/Co-MOFs was synthesized via a facial one-step carbonization method. The prepared MNPCs exhibited high specific surface areas, good chemical stability and high extraction efficiency for interest organophosphorus pesticides (OPPs). The good extraction performance of the MNPCs for interest OPPs can be primarily attributed to π-π interaction and hydrophobic interaction between MNPCs and OPPs. Based on it, MNPCs-based MSPE-GC-FPD method was established for the quantification of five OPPs in fruit samples...
November 7, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30446267/formation-of-by-products-during-chemical-interesterification-of-lipids-detection-and-characterization-of-dialkyl-ketones-by-non-aqueous-reversed-phase-liquid-chromatography-high-resolution-mass-spectrometry-and-gas-chromatography-mass-spectrometry
#2
Valentina Santoro, Claudio Baiocchi, Federica Dal Bello, Daniela Gastaldi, Riccardo Aigotti, Michael Zorzi, Andrea Pellegrino, Emanuele Forte, Francesco Romaniello, Martina Magni, Mauro Fontana, Marco Somenzi, Claudio Medana
A new class of foreign substances present in the unsaponifiable fraction of vegetable oils undergone to chemical interesterification was systematically investigated. Their chemical structure, corresponding to dialkyl ketones (DAK) molecules, was elucidated both by gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-high resolution mass spectrometry (LC-HRMS). An analytical protocol aimed to qualitative and quantitative detection of DAK molecules in vegetable oils of confectionery industry interest was developed...
November 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30442473/simultaneous-determination-of-dietary-isoprenoids-carotenoids-chlorophylls-and-tocopherols-in-human-faeces-by-rapid-resolution-liquid-chromatography
#3
Carla M Stinco, Ana M Benítez-González, Antonio J Meléndez-Martínez, Dolores Hernanz, Isabel M Vicario
An analytical method was validated for the quantitative determination of isoprenoids compounds in faecal samples, based on liquid-liquid extraction from a small aliquot (0.3-0.5 g of sample) and subsequent analysis by Rapid Resolution Liquid Chromatography (RRLC) on a C30 column. An excellent linear response was observed over the range specified for all dietary isoprenoids, as confirmed by the correlation coefficient, which ranged from 0.9977 to 0.9999. LODs ranged from 0.002 μg to 0.036 μg for lutein and α-tocopherol, respectively...
November 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30442471/propanol-sugar-aqueous-biphasic-systems-as-a-suitable-platform-for-biomolecules-extraction
#4
Nosaibah Ebrahimi, Rahmat Sadeghi
Aiming at designing efficient extraction processes, this work proposes the novel aqueous biphasic systems (ABS) composed of sugars and alcohols. The complete liquid-liquid phase diagrams (binodal curves and tie-lines) for several ternary systems of {water + 1-propanol / 2-propanol + sugar (mono- and di-saccharides, and their polyols)} were determined, for the first time. The main factors which affect the phase separation ability of these systems, such as temperature, structure and stereochemistry of sugars, and the alcohol type were discussed...
November 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30429086/extraction-and-quantitative-analysis-of-tropane-alkaloids-in-radix-physochlainae-by-emulsion-liquid-membrane-with-tropine-based-ionic-liquid
#5
Jie Tang, Siwei Liang, Bing Dong, Yao Li, Shun Yao
Emulsion liquid membrane (ELM) coupled with tropine-based ionic liquid was prepared and successfully adopted for the extraction and quantitative analysis of tropane alkaloids (TA) in Radix physochlainae. Effects of formation conditions of ELM were explored and then optimized; the ideal oil-water mass ratio was determined to be 1:2.5, chloroform, Span 80 and 0.05 mol L-1 N-propyl-tropine hexafluorophosphate ([C3 Tr][PF6 ]) aqueous solution were stirred for 30 min with the speed of 1500 r min-1 . In order to extract and enrich TA with ELM efficiently, key factors related with their extraction efficiency such as stirring speed, volume of the extracts (feed solution), migration time and initial concentration of TA were systematically investigated...
November 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30429085/determination-of-short-chain-chlorinated-paraffins-using-comprehensive-two-dimensional-gas-chromatography-coupled-with-low-resolution-mass-spectrometry
#6
Yun Zou, Shan Niu, Liang Dong, Naoki Hamada, Yuki Hashi, Wenlong Yang, Pengjun Xu, Kiyomi Arakawa, Jun Nagata
Short-chain chlorinated paraffins (SCCPs), recently listed as Persistent Organic Pollutants (POPs) under the Stockholm Convention, are contained in commercial chlorinated paraffin (CP) products, which are used in industries such as metalworking fluids, sealants, and textiles. A novel method to determine SCCPs by comprehensive two-dimensional gas chromatography coupled with low resolution mass spectrometry was developed. Calibration curves of response factor versus chlorine content in two chlorine content ranges (R2 were 0...
November 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30424967/polyethyleneimine-modified-hybrid-silica-sorbent-for-hydrophilic-solid-phase-extraction-of-thyreostats-in-animal-tissues
#7
Tingting Wang
In this work, a novel polyethyleneimine-modified hybrid silica material was developed and utilized as a solid support for hydrophilic solid-phase extraction (HILIC SPE) of thyreostats in animal tissue samples. The effects of critical parameters of extraction, including acetonitrile content, pH, sample loading volume, elution volume, sample loading flow rate and elution flow rate were completely optimized. It was found that the polyethyleneimine-modified hybrid silica sorbent displayed a high adsorption capacity of 15...
November 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30424965/matrix-solid-phase-dispersion-based-on-magnetic-ionic-liquids-an-alternative-sample-preparation-approach-for-the-extraction-of-pesticides-from-vegetables
#8
Theodoros G Chatzimitakos, Jared L Anderson, Constantine D Stalikas
In this study, we propose, for the first time, the direct use of a magnetic ionic liquid (MIL) in a matrix solid-phase extraction procedure. Because of the magnetic properties, the MIL can be harvested directly after the extraction step, using a magnet, while its hydrophobic nature makes feasible the extraction of analytes. Raw vegetables of high water content can be analyzed without any pretreatment. The viscous nature of the selected MIL assists in blending with the matrix, while its hydrophobicity facilitates easier separation and retrieval...
November 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30413242/analysis-of-microstructure-effective-diffusivity-relationships-for-the-interparticle-pore-space-in-physically-reconstructed-packed-beds
#9
Dzmitry Hlushkou, Ulrich Tallarek
We evaluate the effective diffusion coefficient in the interparticle pore space of eight physically reconstructed chromatographic packings of fully porous and core-shell particles, employing an analytical formula that involves the three-point microstructural parameter calculated from two-point and three-point correlation functions through an approach based on sampling templates. Diffusivities calculated by the approximate analytical formula are close to those obtained from pore-scale simulations in the reconstructions using a random-walk particle-tracking technique...
November 2, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30446266/systematic-characterization-and-quantification-of-rubiaceae-type-cyclopeptides-in-20-rubia-species-by-ultra-performance-liquid-chromatography-tandem-mass-spectrometry-combined-with-chemometrics
#10
Xuejia Zhang, Qirui Bi, Xingdong Wu, Zhe Wang, Yuanyuan Miao, Ninghua Tan
Rubiaceae-type cyclopeptides (RAs) are one of characteristic constituents isolated from Rubia species, which are candidates of innovative anti-tumor drugs due to their significant bioactivity. However, approaches on the systematic characterization and quantification of RAs are still not available because of low contents and complicated purification. In this study, an ultra performance liquid chromatography coupled triple quadrupole tandem mass spectrometry (UPLC-QqQ-MS/MS) method was established and validated for qualitative and quantitative analysis of 14 RAs (1-14) in 20 Rubia plants from China...
November 1, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30446265/detailed-efficiency-analysis-of-columns-with-a-different-packing-quality-and-confirmation-via-total-pore-blocking
#11
Kim Vanderlinden, Gert Desmet, David S Bell, Ken Broeckhoven
We report on a systematic study involving columns with a clearly different efficiency (4 distinct quality groups) obtained by packing the columns that were C18 bonded and endcapped with a different carbon loading. Using B-term analysis (via peak parking) and theoretical models to estimate the magnitude of the Cm - and Cs -term contributions, it could be concluded that the difference in efficiency among the groups was entirely due to a difference in eddy dispersion. As such, the columns provided an ideal testing ground to verify how well the total pore blocking (TPB)-method can be used to probe differences in packing heterogeneity...
November 1, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30396681/retention-time-prediction-in-thermally-modulated-comprehensive-two-dimensional-gas-chromatography-correcting-second-dimension-retention-time-modeling-error
#12
Roman Jaramillo, Frank L Dorman
Thermodynamic retention modeling to a thermally modulated comprehensive two-dimensional gas chromatography (GC × GC) system run under constant flow is performed. Significant errors in modeled second dimension retention time (tr,2 ) were observed, in line with past work on thermally modulated GC × GC modeling. A comprehensive study of tr,2 modeling error for alkane separations across a wide range of heating ramp rates and carrier gas flow rates was performed. Modeling errors were found to be systematic and a function of analyte elution temperature and mobile phase velocity...
November 1, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30401538/application-and-enantiomeric-residue-determination-of-diniconazole-in-tea-and-grape-and-apple-by-supercritical-fluid-chromatography-coupled-with-quadrupole-time-of-flight-mass-spectrometry
#13
Xinzhong Zhang, Yuechen Zhao, Xinyi Cui, Xinru Wang, Huishan Shen, Zongmao Chen, Chun Huang, Narendra Meruva, Li Zhou, Fang Wang, Luchao Wu, Fengjian Luo
A chiral separation and residue determination method for diniconazole enantiomers in tea, apple, and grape was developed and validated by supercritical fluid chromatography coupled with quadrupole-time-of-flight mass spectrometry (SFC-Q-TOF/MS). The two diniconazole enantiomers were separated on a Chiral CCA column, and the chromatographic conditions (mobile phase proportion and modifier, column temperature, backpressure, and auxiliary solvent) were optimized. The optimal SFC-Q-TOF/MS conditions were selected as a mobile phase of CO2 /isopropanol (IPA) (v/v, 96/4), flow rate at 2...
October 31, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30396680/flow-optimisations-with-increased-channel-thickness-in-asymmetrical-flow-field-flow-fractionation
#14
Joon Seon Yang, Myeong Hee Moon
Retention in flow field-flow fractionation (flow FFF) is generally governed by the combination of crossflow and migration flowrates. Especially for an asymmetrical flow FFF (AF4) channel in which the channel-inlet flow is divided into crossflow and outflow, the separation of low-molecular-weight proteins or macromolecules requires a relatively high crossflow rate along with a very low outflow rate for a reasonable level of resolution, which often leads to a limitation in channel pressure. In this study, the performances of AF4 with increased channel thicknesses have been investigated by adjusting the effective channel flowrates in the asymmetrical channels according to the variation of channel thickness...
October 31, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30391034/a-two-step-heat-treatment-of-cell-disruption-supernatant-enables-efficient-removal-of-host-cell-proteins-before-chromatographic-purification-of-hbc-particles
#15
Zhengjun Li, Jiangxue Wei, Yanli Yang, Lili Liu, Guanghui Ma, Songping Zhang, Zhiguo Su
The thermal stability of HBc particles was systematically investigated for efficient removal of host cell proteins (HCP) by heat treatment before chromatographic step. The HBc particles were found stable up to 80°C for 30 min without any noticeable change in circular dichroism spectra, fluorescence spectra and transmission electron microscope observation. When heating was applied to precipitate the HCP in the cell disruption supernatant of HBc fermentation, the HCP removal effect was more obvious as the temperature went higher...
October 30, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30391036/comprehensive-two-dimensional-gas-chromatography-high-resolution-mass-spectrometry-for-the-analysis-of-substituted-and-unsubstituted-polycyclic-aromatic-compounds-in-environmental-samples
#16
Ifeoluwa Idowu, Wesley Johnson, Olga Francisco, Terry Obal, Chris Marvin, Philippe J Thomas, Courtney D Sandau, Jörg Stetefeld, Gregg T Tomy
Polycyclic aromatic compounds (PACs) consists of multiple compounds and the number of theoretically possible isomers can reach into the thousands. Currently each PAC group is quantified collectively as a single group of compounds. However, individual PACs can reveal important information on how the PACs were formed and this information may be used to determine sources of PACs in environmental samples, It is hypothesized that many of the limitations with characterizing alkylated PACs with one dimensional gas-chromatography (1D GC) can be circumvented using GC × GC (two dimensional gas chromatography)...
October 29, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30389209/a-polyvinyl-alcohol-coated-core-shell-magnetic-nanoparticle-for-the-extraction-of-aminoglycoside-antibiotics-residues-from-honey-samples
#17
Duo Li, Tengfei Li, Lei Wang, Shunli Ji
The authors describe magnetic nanoparticles comprising of a Fe3 O4 core and a polyvinyl alcohol (PVA) coating for use in dispersive solid phase extraction (DSPE) of aminoglycoside antibiotics (AAs). The sorbent was investigated by Transmission electron microscope (TEM), Fourier transform infrared spectrometer (FT-IR), thermo-gravimetric analysis (TGA), nitrogen adsorption-desorption isotherms and so on. The extraction conditions consisting of the proportion of ACN, pH value, buffer concentration and sorbent dosage were optimized...
October 29, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30389211/time-segment-scanning-based-quasi-multiple-reaction-monitoring-mode-by-ultra-performance-liquid-chromatography-coupled-with-quadrupole-time-of-flight-mass-spectrometry-for-quantitative-determination-of-herbal-medicines-moutan-cortex-a-case-study
#18
Xiu-Yang Li, Jin-Di Xu, Shan-Shan Zhou, Ming Kong, Ya-Yun Xu, Ye-Ting Zou, Ya Tang, Li Zhou, Ming-Zhe Xu, Jun Xu, Song-Lin Li
In this study, a time segment scanning-based quasi-multiple reaction monitoring (quasi-MRM) mode was proposed to improve the quantitative performance of UPLC-QTOF-MS/MS. To achieve the quasi-MRM mode, a strategy to select the ion pair (precursor and product ions) of each analyte was adopted as follows. First, a stable and abundant ion by quadrupole was set as precursor ion in MS scan mode. Second, the fragment ions of the precursor ion formed via collision-induced dissociation were measured by time-of-flight (TOF) in MS/MS scan mode; a characteristic, stable and abundant fragment ion (or precursor ion in case of fragment ion unavailable) was designated as the product ion...
October 28, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30389210/continuous-mode-separation-of-fucose-and-2-3-butanediol-using-a-three-zone-simulated-moving-bed-process-and-its-performance-improvement-by-using-partial-extract-collection-partial-extract-recycle-and-partial-desorbent-port-closing
#19
Chung-Gi Lee, Cheol Yeon Jo, Ye Jin Song, Sungyong Mun
If a multi-component monosugar mixture including fucose was used as the substrates for the Klebsiella oxytoca fermentation, it could offer the following two benefits simultaneously; (i) the removal of all monosugars other than fucose, and (ii) the acquisition of 2,3-butanediol (BD). To utilize such two benefits in favor of the economical efficiency of the fucose production process, it is essential to accomplish a high-purity separation between fucose and BD on the basis of a highly-economical mode. To address this issue, we aimed to develop a simulated moving bed (SMB) process for continuous-mode separation of fucose and BD with high purities...
October 28, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/30389207/determination-of-surface-properties-and-gutmann-s-lewis-acidity-basicity-parameters-of-thiourea-and-melamine-polymerized-graphitic-carbon-nitride-sheets-by-inverse-gas-chromatography
#20
T V M Sreekanth, Praveen Kumar Basivi, P C Nagajyothi, G R Dillip, J Shim, T J Ko, K Yoo
Melamine and thiourea-derived graphitic carbon nitrides (M-GCN/T-GCN) were synthesized and characterized. The surface properties were investigated using inverse gas chromatography (IGC) and compared. Net retention volumes of M-GCN and T-GCN were measured with n-alkanes (C5 -C10 ) and polar probes. The London dispersive surface free energies (γs d ), calculated using Schultz and Dorris-Gray methods, decreased linearly with increasing temperature. The specific components of the enthalpy and entropy of adsorption for the polar probes were obtained using the Schultz, Dong, and Sawyer-Brookman methods...
October 27, 2018: Journal of Chromatography. A
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