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Journal of Chromatography. A

Jan Partyka, Jana Krenkova, Richard Cmelik, Frantisek Foret
The labeling by amino acids and peptides was investigated for sensitive and fast analyses of oligosaccharides and N-linked glycans by capillary electrophoresis-mass spectrometry (CE-MS). Peptide tags with a various number of histidine residues were tested for maltooligosaccharide labeling in order to investigate the effect of the size of labels and a number of charges on CE-MS analysis. Nevertheless, the reductive amination labeling of N-linked glycans by a hexahistidine tag resulted in a multiple products formation, therefore a peptide tag was modified by hydrazine functionality in order to perform labeling by hydrazone formation chemistry...
May 16, 2018: Journal of Chromatography. A
Peilin Yang, Lu Bai, Wenqin Wang, John Rabasco
Hydrophobically modified ethylene oxide urethane (HEUR) rheology modifiers are polymers used widely in waterborne coatings and other consumer products. The incorporation of hydrophobic end-groups significantly affects the thickening performance of HEURs. Therefore, understanding the degree of incorporation of hydrophobic end-groups on the polymer chain can help gain important insights on the structure/property relationship for HEUR rheology modifiers. A comprehensive two-dimensional liquid chromatography (2D-LC) method was developed for separating polymeric HEUR rheology modifiers based on the number of hydrophobic end-groups incorporated on the polymer chain...
May 16, 2018: Journal of Chromatography. A
Maxim M Trubyanov, Georgy M Mochalov, Sergey S Suvorov, Egor S Puzanov, Anton N Petukhov, Ilya V Vorotyntsev, Vladimir M Vorotyntsev
The current study focuses on the processes involved during the flow conversion of water into acetylene in a calcium carbide reaction cell for the trace moisture analysis of ammonia by reaction gas chromatography. The factors negatively affecting the reproducibility and the accuracy of the measurements are suggested and discussed. The intramolecular reaction of the HOCaCCH intermediate was found to be a side reaction producing background acetylene during the contact of wet ammonia gas with calcium carbide. The presence of the HOCaCCH intermediate among the reaction products is confirmed by an FTIR spectral study of calcium carbide powder exposed to wet gas...
May 16, 2018: Journal of Chromatography. A
Idris Guven, Orhan Gezici, Mevlut Bayrakci, Massimo Morbidelli
New cation exchanger monolithic stationary phases were prepared by immobilization of three different calixarene derivatives (i.e. tetracarboxylate calix[4]arene, CLX-COO, tetrasulfonate calix[4]arene, CLX-SO3 , and tetraphosphonate calix[4]arene, CLX-PO4 ) onto a monolithic cryogel support (i.e. poly(2-hydroksyethylmethacrilate-co-glycidyl methacrylate, P) and investigated with respect to preparative protein chromatography. The obtained monoliths were characterized through various techniques such as FTIR spectroscopy, isoelectric point measurements, titrimetric analyses, and mercury intrusion porosimetry...
May 16, 2018: Journal of Chromatography. A
Minjeong Gu, Keunchang Cho, Seong Ho Kang
The migration behavior of organic fluorescent dyes (i.e., crystal violet, methyl violet base, methyl violet B base, rhodamine 6G, and rhodamine B base) in non-aqueous capillary electrophoresis (NACE) was investigated by focusing on the physicochemical properties of various organic solvents [ethanol, methanol, 2-propanol, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)] in background electrolyte (BGE). Laser-induced fluorescence (LIF) and UV/Vis detectors were employed to observe both the migration time of organic dyes and the electroosmotic flow (EOF) in NACE, respectively...
May 15, 2018: Journal of Chromatography. A
Radosław Ł Gwarda, Tadeusz H Dzido
In our previous papers we have investigated the influence of the mobile phase composition on mechanism of retention, selectivity and efficiency of peptide separation in various high-performance thin-layer chromatography (HPTLC) systems with commercially available silica-based adsorbents. We have also investigated the influence of pH of the mobile phase buffer on migration and separation of peptides in pressurized planar electrochromatography (PPEC). Here we investigate the influence of concentration of ion-pairing additive, and concentration and type of organic modifier of the mobile phase on migration of peptides in PPEC system with octadecyl silica-based adsorbent, and with the same set of the solutes as before...
May 15, 2018: Journal of Chromatography. A
T Brooijmans, R Okhuijsen, I Oerlemans, P J Schoenmakers, R Peters
Pyrolysis - gas chromatography - (PyGC) is a common method to analyse the composition of natural and synthetic resins. The analysis of acid functionality in, for example, waterborne polyacrylates and polyurethanes polymers has proven to be difficult due to solubility issues, inter- and intramolecular interaction effects, lack of detectability in chromatographic analysis, and lack of thermal stability. Conventional analytical techniques, such as PyGC, cannot be used for the direct detection and identification of acidic monomers, due to thermal rearrangements that take place during pyrolysis...
May 14, 2018: Journal of Chromatography. A
Mohammad Faraji, Mohammadrezza Hamdamali, Fezzeh Aryanasab, Meisam Shabanian
In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L-1 with a determination coefficient (R2 ) of 0...
May 9, 2018: Journal of Chromatography. A
Huixia Huo, Yao Liu, Wenjing Liu, Jing Sun, Qian Zhang, Yunfang Zhao, Jiao Zheng, Pengfei Tu, Yuelin Song, Jun Li
The quality of herbal medicines (HMs) is the prerequisite for their pronounced therapeutic outcomes in clinic, and multi-component (also known as quality markers, Q-markers) quantification has been widely emphasized as a viable means for quality evaluation. Because of the chemical diversity, the quality control practices are extensively dampened by four principal technical bottlenecks, including the lack of authentic compounds, large polarity span, extensive concentration range, and signal misrecognition for those potential Q-markers...
May 9, 2018: Journal of Chromatography. A
Giacomo Musile, Lucia Cenci, Elena Piletska, Rossella Gottardo, Alessandra M Bossi, Federica Bortolotti
The aim of the present work was to develop a novel in-house mixed-mode SPE sorbent to be used for the HPLC-Ion TrapMS determination of 16 basic drugs in urine. By using a computational modelling, a virtual monomer library was screened identifying three suitable functional monomers, methacrylic acid (MAA), itaconic acid (IA) and 2-acrylamide-2-methylpropane sulfonic acid (AMPSA), respectively. Three different sorbents were then synthetized based on these monomers, and using as cross-linker trimethylolpropane trimethacrylate (TMPTMA)...
May 9, 2018: Journal of Chromatography. A
Kai Zhao, Dongqing Li
The ionic liquids (ILs) as the environmentally benign solvents show great potentials in microemulsion carrier systems and have been widely used in the biochemical and pharmaceutical fields. In the work, the ionic liquid-in-water microemulsions were fabricated by using two kinds of hydrophobic ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF6 ] and 1-Hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6 ] with Tween 20. The ionic liquid droplets in water experience the dielectrophoretic (DEP) forces induced by applying electrical field via a nano-orifice and a micron orifice on the opposite channel walls of a microchannel...
May 9, 2018: Journal of Chromatography. A
Zhihui Zhou, Yanqing Fu, Qian Qin, Xin Lu, Xianzhe Shi, Chunxia Zhao, Guowang Xu
A novel, magnetic and mesoporous Fe3 O4 @PEI-MOF-5 material was synthesized for the effective enrichment of malachite green (MG) and crystal violet (CV) in fish samples. The Fe3 O4 @PEI-MOF-5 material was prepared by a facile two-step solvothermal approach in which Fe3 O4 @PEI and MOF-5 were connected through chemical bonds. Characterization of the newly synthesized Fe3 O4 @PEI-MOF-5 material was performed by Fourier transform infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy...
May 9, 2018: Journal of Chromatography. A
Jozef Šesták, Regula Theurillat, Friederike A Sandbaumhüter, Wolfgang Thormann
Head-column field-amplified sample stacking of cations from a low conductivity sample followed by enantiomeric separation using negatively charged chiral selectors was studied experimentally and with computer simulation. Aspects investigated include the direct electrokinetic injection of the analytes into the background electrolyte, the use of a selector free buffer plug, the contribution of complexation within the buffer plug and the application of an additional water plug between sample and buffer plug. Attention was paid for changes of ionic strength which is known to have a significant impact on complexation and thus effective mobility...
May 9, 2018: Journal of Chromatography. A
David Achaintre, Audrey Gicquiau, Liang Li, Sabina Rinaldi, Augustin Scalbert
Polyphenols constitute one of the most complex classes of phytochemicals in the human diet and have been suggested to play a role in the prevention of chronic diseases such as cardiovascular diseases, diabetes and cancers. However, evidence from epidemiological studies is still needed to better understand their role in disease prevention. To do so, robust methods for the accurate measurement of these molecules in large series of samples are needed. We report here the development of a highly-sensitive method based on differential isotope labelling with 13 C- and 12 C-dansyl chloride for the analysis of 38 structurally diverse polyphenols in 50 μL plasma by tandem mass spectrometry with limits of quantification varying between 0...
May 9, 2018: Journal of Chromatography. A
Mohammad T Jafari, Mohammad Saraji, Mansoure Kermani
Carbon-silica hybrid nanofibers as high performance coatings for solid-phase microextraction fibers were used for analyzing some pesticides by using gas chromatography-corona discharge ion mobility spectrometry. To that end, the fibers were prepared by carbonizing sol-gel based on electrospun polyacrylonitrile and tetraethyl orthosilicate nanofibers as carbon and silica precursors, respectively. Different parameters affecting the electrospinning and the extraction processes including spinning distance, voltage, feeding rate, stirring rate, salt concentration, temperature and extraction time were optimized by response surface methodology...
May 8, 2018: Journal of Chromatography. A
Wiebke Rudolph, Daniela Remane, Dirk K Wissenbach, Frank T Peters
Endophyte fungi (e.g. Epichloë ssp. and Neotyphodium ssp.) in symbiosis with pasture grasses (e.g. Festuca arundinacaea and Lolium perenne) can produce toxic alkaloids, which are suspected to be involved in equine diseases such as fescue toxicosis, ryegrass staggers, and equine fescue oedema. The aim of this study was, therefore, to develop and validate a quantification method for these and related alkaloids: ergocristine, ergocryptine, ergotamine, ergovaline, lolitrem B, lysergic acid, N-acetylloline, N-formylloline, peramine, and paxilline in horse serum...
May 7, 2018: Journal of Chromatography. A
Shijuan Zhang, Fengli Lu, Xiaoyun Ma, Mingbo Yue, Yanxin Li, Jiammin Liu, Jinmao You
MCM-48 mesoporous silica was functionalized with dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, a quaternary ammonium salt with a long hydrophobic chain, to prepare a new sorbent for the dispersive solid-phase extraction (DSPE) of seven endocrine disrupting compounds (EDCs) including 4-hexylphenol, 4-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol and estriol in water. A series of differently functionalized MCM-48 materials were also synthesized, and they served as reference materials to study the mechanism...
May 7, 2018: Journal of Chromatography. A
Claudia Oellig, Klara Brändle, Wolfgang Schwack
Mono- and diacylglycerol (MAG and DAG) emulsifiers, also known as food additive E 471, are widely used to adjust techno-functional properties in various foods. Besides MAGs and DAGs, E 471 emulsifiers additionally comprise different amounts of triacylglycerols (TAGs) and free fatty acids (FFAs). MAGs, DAGs, TAGs and FFAs are generally determined by high-performance liquid chromatography (HPLC) or gas chromatography (GC) coupled to mass selective detection, analyzing the individual representatives of the lipid classes...
May 7, 2018: Journal of Chromatography. A
Jiwon Eom, Gahyeon Lee, Dong Soo Lee
and theoretical studies were conducted to investigate low and non-linear responses in sub-micro molar-level suppressed ion chromatography with a hydroxide eluent. A calculated response was derived using experimentally determined detector effluent ion composition data and compared with measured experimental responses. The calibration curve was non-linear, and its slope varied considerably with different instrumental setups and operating conditions. The non-linearity of the solution conductivity response was determined by two acid-base equilibria of water and carbonic acid, and fluoride ion...
May 5, 2018: Journal of Chromatography. A
Reinhard Oertel, Julien Baldauf, Julia Rossmann
A rapid and sensitive hydrophilic interaction liquid chromatography (HILIC)-tandem mass spectrometry method was developed and fully validated for the simultaneous determination of the antidiabetic drug metformin and six further pharmaceuticals (atenolol, gabapentin, levofloxacin, ciprofloxacin, propranolol and trimethoprim) in influent and effluent wastewater. Five deuterated related compounds were used as internal standards in order to control the extraction, injection and ionization variability. Two solid phase extraction methods and Oasis HLB 1cc cartridge, using only 1 mL sample with acid or basic pH-value were optimized and compared in order to match the specificity of both influent and effluent wastewater matrixes...
May 4, 2018: Journal of Chromatography. A
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