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Journal of Chromatography. A

Xiuting Hu, Yu Wang, Chengmei Liu, Zhengyu Jin, Yaoqi Tian
Polyethylene glycol (PEG) was further applied for fractionating dextrin prepared from cassava starch. The initial dextrin concentration and pH of the dextrin solutions were crucially considered in this study with the average molecular-weight dispersity (DMa) as the index. The results showed that the initial dextrin concentration significantly affected the mass fraction and the molecular weight distribution of each dextrin fraction obtained from gradient PEG precipitation. However, the initial dextrin concentration, which ranged from 0...
November 11, 2017: Journal of Chromatography. A
Bob W J Pirok, Stef R A Molenaar, Rianne E van Outersterp, Peter J Schoenmakers
Computer-aided method-development programs require accurate models to describe retention and to make predictions based on a limited number of scouting gradients. The performance of five different retention models for hydrophilic-interaction chromatography (HILIC) is assessed for a wide range of analytes. Gradient-elution equations are presented for each model, using Simpson's Rule to approximate the integral in case no exact solution exists. For most compound classes the adsorption model, i.e. a linear relation between the logarithm of the retention factor and the logarithm of the composition, is found to provide the most robust performance...
November 11, 2017: Journal of Chromatography. A
Congying Wen, Mengmeng Li, Wangbo Li, Zizhou Li, Wei Duan, Yulong Li, Jie Zhou, Xiyou Li, Jingbin Zeng
The content of gasoline fraction in oil samples is not only an important indicator of oil quality, but also an indispensable fundamental data for oil refining and processing. Before its determination, efficient preconcentration and separation of gasoline fractions from complicated matrices is essential. In this work, a thin layer of graphene (G) was deposited onto oriented ZnO nanorods (ZNRs) as a SPME coating. By this approach, the surface area of G was greatly enhanced by the aligned ZNRs, and the surface polarity of ZNRs was changed from polar to less polar, which were both beneficial for the extraction of gasoline fractions...
November 11, 2017: Journal of Chromatography. A
Anna Baglai, Andrea F G Gargano, Jan Jordens, Ynze Mengerink, Maarten Honing, Sjoerd van der Wal, Peter J Schoenmakers
Recent advancements in separation science have resulted in the commercialization of multidimensional separation systems that provide higher peak capacities and, hence, enable a more-detailed characterization of complex mixtures. In particular, two powerful analytical tools are increasingly used by analytical scientists, namely online comprehensive two-dimensional liquid chromatography (LC×LC, having a second-dimension separation in the liquid phase) and liquid chromatography-ion mobility-spectrometry (LC-IMS, second dimension separation in the gas phase)...
November 10, 2017: Journal of Chromatography. A
S Agatonovic-Kustrin, D W Morton, A Adam, H H Mizaton, H Zakaria
The steady increase of diabetes is becoming a major burden on health care systems. As diabetic complications arise from oxidative stress, an antioxidant therapy along with anti-diabetic drugs is recommended. Myrmecodia or ant plant is highly valued as a traditional medicine in West Papua. It is used as an alternative treatment for diabetes, as the substances produced by ants can reduce blood sugar levels. The aim of this study was to develop and establish high-performance thin-layer chromatographic (HPTLC)-bioautographic methods to measure the antioxidant and hypoglycemic effects in different extracts from Myrmecodia platytyrea and to compare them with sterol content...
November 10, 2017: Journal of Chromatography. A
Syntia Fayad, Philippe Morin, Reine Nehmé
Elastase, collagenase, hyaluronidase and tyrosinase, are very interesting enzymes due to their direct implication in skin aging and as therapeutic hits. Different techniques can be used to study these enzymes and to evaluate the influence of effectors on their kinetics. Nowadays, analytical techniques have become frequently used tools for miniaturizing enzyme assays. The main intention of this article is to review chromatographic and electrophoretic tools that study the four enzymes above mentioned. More specifically, the use of high-performance liquid chromatography and capillary electrophoresis and their derivative techniques for monitoring these enzymes will be investigated...
November 9, 2017: Journal of Chromatography. A
Javier González-Sálamo, Bárbara Socas-Rodríguez, Javier Hernández-Borges, Miguel Ángel Rodríguez-Delgado
In this work, the first application of core-shell poly(dopamine) magnetic nanoparticles as sorbent for the extraction of a group of eleven phthalic acid esters of interest (i.e. diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP), bis-isopentyl phthalate (DIPP), bis-n-pentyl phthalate (DNPP), benzylbutyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di-(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP)) and one adipate (bis (2-ethylhexyl) adipate, DEHA) from different water samples (Milli-Q, mineral, tap, pond and waste water) is proposed...
November 8, 2017: Journal of Chromatography. A
Andreas Schoenborn, Pascal Schmid, Sarah Bräm, Georg Reifferscheid, Marina Ohlig, Sebastian Buchinger
The planar yeast estrogen screen (p-YES) can serve as a highly valuable and sensitive screening tool for the detection of estrogenic compounds in various sample matrices such as water and wastewater, personal care products and foodstuff. The method combines the separation of sample constituents by thin layer chromatography with the direct detection of estrogenic compounds on the surface of the HPTLC-plate. The previous protocol using the immersion of a normal phase silica HPTLC-plate in a cell suspension for bio-autography resulted in blurred signals due to the accelerated diffusion of compounds on the wet surface of the HPTLC-plate...
November 7, 2017: Journal of Chromatography. A
Ji-Woo Chung, Kyung-Min Kim, Tae-Ung Yoon, Seung-Ik Kim, Tae-Sung Jung, Sang-Sup Han, Youn-Sang Bae
A novel power partial-discard (PPD) strategy was developed as a variant of the partial-discard (PD) operation to further improve the separation performance of the simulated moving bed (SMB) process. The PPD operation varied the flow rates of discard streams by introducing a new variable, the discard amount (DA) as well as varying the reported variable, discard length (DL), while the conventional PD used fixed discard flow rates. The PPD operations showed significantly improved purities in spite of losses in recoveries...
November 7, 2017: Journal of Chromatography. A
Ning Yan, Xiao-Fang Wan, Xin-Sheng Chai, Run-Quan Chen, Chun-Xia Chen
This paper reports on an ionic-liquid assisted headspace gas chromatographic (HS-GC) for the determination of the content of alkyl ketene dimer (AKD) in its latex samples, in which the GC system was equipped with a thermal conductivity detector (TCD). The method was based on the AKD hydrolysis conducted in 1-butyl-3-methylimidazolium chloride (ionic-liquid) added medium at 100°C for 10min in a closed headspace sample vial, and the measured CO2 (the resulting product of the hydrolysis) by HS-GC. The results showed that the present method has a good measurement precision (RSD <2...
November 7, 2017: Journal of Chromatography. A
Kyunil Rah, Sujeong Han, Jaeyeong Choi, Chul Hun Eum, Seungho Lee
We investigate an explicit role of the ionic strength in the retention behaviors of polystyrene (PS) latex particles in sedimentation field-flow fractionation (SdFFF) by hinging upon the retention theory recently developed [1] asR=(Ro+vb(*))/(1+vb(*)). Here R is an experimental retention ratio, and Ro is the analytical expression of the standard retention theory based on the parabolic flow velocity. The reduced boundary velocityvb(*) is expressed in terms of the ionic strength I of the carrier liquid as vb(*)=vb,o(*)/(1+εI), where vb,o(*)=0...
November 7, 2017: Journal of Chromatography. A
Gabriel Isaacman-VanWertz, Donna T Sueper, Kenneth C Aikin, Brian M Lerner, Jessica B Gilman, Joost A de Gouw, Douglas R Worsnop, Allen H Goldstein
Chromatography provides important detail on the composition of environmental samples and their chemical processing. However, the complexity of these samples and their tendency to contain many structurally and chemically similar compounds frequently results in convoluted or poorly resolved data. Data reduction from raw chromatograms of complex environmental data into integrated peak areas consequently often requires substantial operator interaction. This difficulty has led to a bottleneck in analysis that increases analysis time, decreases data quality, and will worsen as advances in field-based instrumentation multiply the quantity and informational density of data produced...
November 7, 2017: Journal of Chromatography. A
Zhiqiang Wang, Seung Hwan Hwang, Soon Sung Lim
In the present study, a novel hyphenation of ultrafiltration (UF), high-speed countercurrent chromatography (HSCCC), and high-performance liquid chromatography (HPLC) was developed for comprehensive profiling and characterization of the minor tyrosinase inhibitors from Gastrodia elata (GE). A small quantity of GE extract was first fractionated by HSCCC, using elution solvents with a wide range of polarities to enrich minor compounds; then, the fractions were profiled by UF-HPLC to generate a comprehensive 2D chromatogram of the distribution of bioactive components...
November 6, 2017: Journal of Chromatography. A
Xianshuang Meng, Hua Bai, Teng Guo, Zengyuan Niu, Qiang Ma
Comprehensive identification and quantitation of 100 multi-class regulated ingredients in cosmetics was achieved using ultra-high-performance liquid chromatography (UHPLC) coupled with hybrid quadrupole-Orbitrap high-resolution mass spectrometry (Q-Orbitrap HRMS). A simple, efficient, and inexpensive sample pretreatment protocol was developed using ultrasound-assisted extraction (UAE), followed by dispersive solid-phase extraction (dSPE). The cosmetic samples were analyzed by UHPLC-Q-Orbitrap HRMS under synchronous full-scan MS and data-dependent MS/MS (full-scan MS(1)/dd-MS(2)) acquisition mode...
November 6, 2017: Journal of Chromatography. A
Michelle M Cerreta, Kevin J Johnson, Braden C Giordano
Typical trace vapor analysis involves sorbent trapping, followed by desorption and chromatographic separation. This communication describes a method for streamlining this process by combining sorbent sampling/preconcentration with partial separation achieved through temperature-programmed thermal desorption. A novel sorbent trap was formulated in which tubular glass liners for a programmable-temperature gas chromatograph inlet were coated with a sol-gel based polymer stationary phase synthesized from methyltrimethoxysilane precursor and installed into the inlet, which was directly connected to a mass-selective detector by a fused silica capillary transfer line...
November 4, 2017: Journal of Chromatography. A
Sergio Santana-Viera, Rayco Guedes-Alonso, Zoraida Sosa-Ferrera, José Juan Santana-Rodríguez, Abuzar Kabir, Kenneth G Furton
Every year, hundreds of tons of organic pollutants reach the environment through effluents released from wastewater treatment plants worldwide, and many of these compounds have harmful effects on the aquatic ecosystem. A new class of emerging pollutants of high concern is cytostatic drugs, which are designed to treat different types of cancers by attacking cells. Environmental concentrations of cytostatic drugs are known to be in the range of ngL(-1), and for this reason, it is imperative to develop analytical methods of extraction and preconcentration to allow for subsequent instrumental analysis of these drugs...
November 4, 2017: Journal of Chromatography. A
Nicole E Heshka, Joanne M Choy, Jinwen Chen
A modification to American Society for Testing and Materials (ASTM) method D5623 is proposed to enable successful and repeatable analysis of heavy crude oil samples. A two-dimensional gas chromatography configuration was implemented, with separation of sulphur compounds occurring on two columns. A Deans switch is used to enable heart-cutting of volatile sulphur compounds onto a DB-Sulfur stationary phase, and separation occurs concurrently with the backflushing of the primary column. The use of a sulphur-selective detector increases selectivity, and 22 volatile sulphur species are quantified in less than 15min, which is almost half the time of the original ASTM method...
November 4, 2017: Journal of Chromatography. A
Hui Li, Zejun Jiang, Xiaolin Cao, Hang Su, Hua Shao, Fen Jin, A M Abd El-Aty, Jing Wang
Herein, an accurate and reliable isotope-labelled internal standard method was developed and validated for simultaneous determination of three polar pesticide adjuvants, namely 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone in plant-derived agro-products. Matrices, including apple, cabbage, tomato, cucumber, rice, and wheat were extracted with a modified quick, easy, cheap, effective, rugged, and safe "QuEChERS" method and purified with a new clean-up sorbent (Z-Sep). A hydrophilic interaction liquid chromatography column (HILIC), exhibiting a lipophilic-hydrophilic character, was used to separate the three analytes over 10min using liquid chromatography-tandem mass spectrometry (LC-MS/MS)...
November 2, 2017: Journal of Chromatography. A
Tinh Le, Francesc A Esteve-Turrillas, Sergio Armenta, Miguel de la Guardia, Guillermo Quiñones-Reyes, Antonio Abad-Fuentes, Antonio Abad-Somovilla
Specific monoclonal antibodies were coupled with magnetic Sepharose-based beads and used, for the first time. The methodology was applied to preconcentrate anatoxin-a from water and the later determination by ion mobility spectrometry (IMS). Dispersive magnetic immunoaffinity (d-MagIA) extraction methodology provided a limit of detection of 0.02μgL(-1) and a satisfactory precision with a relative standard deviation lower than 15%. Recoveries were evaluated at 0.5, 1.0 and 5.0μgL(-1) anatoxin-a with quantitative values from 91 to 115%...
November 1, 2017: Journal of Chromatography. A
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