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Journal of Chromatography. A

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https://www.readbyqxmd.com/read/28213986/investigation-of-the-temperature-dependence-of-water-adsorption-on-silica-based-stationary-phases-in-hydrophilic-interaction-liquid-chromatography
#1
Endre Bartó, Attila Felinger, Pavel Jandera
In the present work, the adsorption of water was investigated in aqueous normal-phase liquid chromatography on Cogent Silica C and Cogent Phenyl hydride stationary phases at different temperatures by frontal analysis - using coulometric Karl Fischer titration - to compare the temperature dependence of adsorption of water from aqueous acetonitrile. The Cogent Silica-C and Cogent Phenyl Hydride columns have a silicon hydride surface (silica hydride) with less than 2% free silanol group; therefore, they do not have a strong association with water...
February 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28202193/comprehensive-three-dimensional-gas-chromatography-mass-spectrometry-separation-of-diesel
#2
Frank Cheng-Yu Wang
Diesel, a complex hydrocarbon mixture, was examined using comprehensive two-dimensional gas chromatography (GC×GC) and a field ionization mass spectrometer (FIMS), which preferentially yields molecular ions, providing an extra dimension for component separation. Molecular ions collected at low mass resolution can be assigned an NM-class (Nominal Mass-class) value that does not completely express hydrogen deficiency. In contrast to formulae and Z-class assignments that are possible from ultrahigh mass resolution, NM-class assignments are not unambiguous; however, the separation provided by GC×GC can result in coelution of components that differ in NM-class...
February 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28202192/ordered-mesoporous-silica-functionalized-with-%C3%AE-cyclodextrin-derivative-for-stereoisomer-separation-of-flavanones-and-flavanone-glycosides-by-nano-liquid-chromatography-and-capillary-electrochromatography
#3
Mariana Silva, Damián Pérez-Quintanilla, Sonia Morante-Zarcero, Isabel Sierra, María Luisa Marina, Zeineb Aturki, Salvatore Fanali
In this paper a chiral stationary phase (CSP) was prepared by the immobilization of a β-CD derivative (3,5-dimethylphenylcarbamoylated β-CD) onto the surface of amino-functionalized spherical ordered mesoporous silica (denoted as SM) via a urea linkage using the Staudinger reaction. The CSP was packed into fused silica capillaries 100μm I.D. and evaluated by means of nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) using model compounds for the enantio- and the diastereomeric separation...
February 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28193466/three-dimensional-ionic-liquid-functionalized-magnetic-graphene-oxide-nanocomposite-for-the-magnetic-dispersive-solid-phase-extraction-of-16-polycyclic-aromatic-hydrocarbons-in-vegetable-oils
#4
Yun Zhang, Hua Zhou, Zhe-Hua Zhang, Xiang-Lun Wu, Wei-Guo Chen, Yan Zhu, Chun-Fu Fang, Yong-Gang Zhao
In this paper, a novel three-dimensional ionic liquid functionalized magnetic graphene oxide nanocomposite (3D-IL@mGO) was prepared, and used as an effective adsorbent for the magnetic dispersive solid phase extraction (MSPE) of 16 polycyclic aromatic hydrocarbons (PAHs) in vegetable oil prior to gas chromatography-mass spectrometry (GC-MS). The properties of 3D-IL@mGO were characterized by scanning electron micrographs (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM). The 3D-IL@mGO, functionalized by ionic liquid, exhibited high adsorption toward PAHs...
February 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28190595/fractionated-dynamic-headspace-sampling-in-the-analysis-of-matrices-of-vegetable-origin-in-the-food-field
#5
Erica Liberto, Cecilia Cagliero, Chiara Cordero, Patrizia Rubiolo, Carlo Bicchi, Barbara Sgorbini
Recent technological advances in dynamic headspace sampling (D-HS) and the possibility to automate this sampling method have lead to a marked improvement in its the performance, a strong renewal of interest in it, and have extended its fields of application. The introduction of in-parallel and in-series automatic multi-sampling and of new trapping materials, plus the possibility to design an effective sampling process by correctly applying the breakthrough volume theory, have make profiling more representative, and have enhanced selectivity, and flexibility, also offering the possibility of fractionated enrichment in particular for high-volatility compounds...
February 7, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28193468/using-the-fundamentals-of-adsorption-to-understand-peak-distortion-due-to-strong-solvent-effect-in-hydrophilic-interaction-chromatography
#6
Fabrice Gritti, Jyotsna Sehajpal, Jacob Fairchild
The peak distortion observed in hydrophilic interaction chromatography (HILIC) may be caused by the sample diluent to mobile phase mismatch. The United States Pharmacopeia (USP) method for organic impurities in cetirizine HCl tablets calls for such a mismatch, having a higher concentration of strong solvent in the sample diluent than in the mobile phase. A significant peak deformation is reported for cetirizine (a second-generation antihistamine) when it is purified on a Ethylene Bridged Hybrid (BEH) HILIC column (4...
February 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28189260/multivariate-analysis-of-variance-of-designed-chromatographic-data-a-case-study-involving-fermentation-of-rooibos-tea
#7
Federico Marini, Dalene de Beer, Nico A Walters, André de Villiers, Elizabeth Joubert, Beata Walczak
An ultimate goal of investigations of rooibos plant material subjected to different stages of fermentation is to identify the chemical changes taking place in the phenolic composition, using an untargeted approach and chromatographic fingerprints. Realization of this goal requires, among others, identification of the main components of the plant material involved in chemical reactions during the fermentation process. Quantitative chromatographic data for the compounds for extracts of green, semi-fermented and fermented rooibos form the basis of preliminary study following a targeted approach...
February 4, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28190596/facile-and-fast-preparation-of-low-cost-silica-supported-graphitic-carbon-nitride-for-solid-phase-extraction-of-fluoroquinolone-drugs-from-environmental-waters
#8
Andrea Speltini, Federica Maraschi, Roberta Govoni, Chiara Milanese, Antonella Profumo, Lorenzo Malavasi, Michela Sturini
The analytical application of silica-supported graphitic carbon nitride (g-C3N4@silica) for solid-phase extraction (SPE) of fluoroquinolone (FQ) pollutants from water is presented for the first time. g-C3N4@silica was easily and quickly prepared by one-pot thermal condensation of dicyandiamide and characterized by powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and surface area measurements. The novel composite was applied as sorbent for SPE of FQs from water prior high-performance liquid chromatography with fluorescence detection...
February 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28189259/capillary-electrophoresis-investigation-on-equilibrium-between-polymer-related-and-surfactant-related-species-in-aqueous-polymer-surfactant-solutions
#9
Yefan Wu, Miaomiao Chen, Yun Fang, Meng Zhu
It was inferred from aqueous solution behavior of nonionic polymers and anionic surfactants that the formation of charged polymer-bound surfactant micelle above critical aggregation concentration (cac) and the formation of free surfactant micelle beyond polymer saturation point (psp), but there was still a lack of direct experimental evidence for the considered equilibrium chemical species. Three modes of capillary electrophoresis are applied in this paper to study the complexation between nonionic polymers, polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG), and sodium dodecylbenzenesulfonate (SDBS) by successfully distinguishing the imaginary charged polymer-bound SDBS micelle from nonionic polymer and SDBS molecule...
February 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28193470/evaluation-of-layered-double-hydroxide-graphene-hybrid-as-a-sorbent-in-membrane-protected-stir-bar-supported-micro-solid-phase-extraction-for-determination-of-organochlorine-pesticides-in-urine-samples
#10
Muhammad Sajid, Chanbasha Basheer, Muhammad Daud, Abdulnaser Alsharaa
In this work, the potential of layered double hydroxide/graphene (LDH-G) hybrid as a sorbent for extraction and preconcentration of fifteen organochlorine pesticides (OCPs) in urine samples was evaluated. The LDH-G hybrid was synthesized by co-precipitation method and it was then characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The sorbent was then employed in membrane-protected stir-bar supported micro-solid-phase extraction (SB-μ-SPE) of OCPs in urine samples...
February 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28179080/simultaneous-determination-of-13-carotenoids-by-a-simple-c18-column-based-ultra-high-pressure-liquid-chromatography-method-for-carotenoid-profiling-in-the-astaxanthin-accumulating-haematococcus-pluvialis
#11
Hui Jin, Yong Min Lao, Jin Zhou, Huai Jin Zhang, Zhong Hua Cai
A simple ultra-high-pressure liquid chromatography (UHPLC) method for rapidly and simultaneously identifying thirteen carotenoids in Haematococcus pluvialis was developed in this study. The method is capable of effectively separating two astaxanthin isomers, two ζ-carotene isomers, and three phytoene isomers on two simple C18 columns within 9 and 12min only by using methanol and acetonitrile, respectively. To our best knowledge, this is the rapidest method for these carotenoid isomers, currently. Using this method, carotenoid profiling in the astaxanthin-accumulating H...
February 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28179079/exploiting-charge-differences-for-the-analysis-of-challenging-post-translational-modifications-by-capillary-electrophoresis-mass-spectrometry
#12
Klaus Faserl, Bettina Sarg, Verena Maurer, Herbert H Lindner
Reversed-phase high-performance liquid chromatography (RP-HPLC) in combination with mass spectrometry (MS) is typically employed for mapping modifications in proteins and peptides. Here we applied a low-flow capillary electrophoresis (CE) -electrospray ionization interface coupled to Orbitrap mass spectrometers to analyze challenging modifications such as asparagine deamidation, aspartate isomerization, arginine citrullination, and phosphopeptide isomers. We achieved excellent resolution of asparagine (Asn), aspartic acid (Asp) and isoaspartic acid (iso-Asp) containing peptides using a synthetic peptide mixture...
February 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28173926/chromatographic-properties-plot-multicapillary-columns
#13
O A Nikolaeva, Y V Patrushev, V N Sidelnikov
Multicapillary columns (MCCs) for gas chromatography make it possible to perform high-speed analysis of the mixtures of gaseous and volatile substances at a relatively large amount of the loaded sample. The study was performed using PLOT MCCs for gas-solid chromatography (GSC) with different stationary phases (SP) based on alumina, silica and poly-(1-trimethylsilyl-1-propyne) (PTMSP) polymer as well as porous polymers divinylbenzene-styrene (DVB-St), divinylbenzene-vinylimidazole (DVB-VIm) and divinylbenzene-ethylene glycol dimethacrylate (DVB-EGD)...
February 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28213987/superficially-porous-particles-with-1000%C3%A3-pores-for-large-biomolecule-high-performance-liquid-chromatography-and-polymer-size-exclusion-chromatography
#14
Brian M Wagner, Stephanie A Schuster, Barry E Boyes, Taylor J Shields, William L Miles, Mark J Haynes, Robert E Moran, Joseph J Kirkland, Mark R Schure
To facilitate mass transport and column efficiency, solutes must have free access to particle pores to facilitate interactions with the stationary phase. To ensure this feature, particles should be used for HPLC separations which have pores sufficiently large to accommodate the solute without restricted diffusion. This paper describes the design and properties of superficially porous (also called Fused-Core(®), core shell or porous shell) particles with very large (1000Å) pores specifically developed for separating very large biomolecules and polymers...
January 31, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28209347/high-resolution-mass-spectrometry-based-method-applicable-for-a-wide-range-of-3-hydroxy-3-methyl-glutaryl-coenzyme-a-reductase-inhibitors-in-blood-serum-including-intermediates-and-products-of-the-cholesterol-biosynthetic-pathway
#15
Vít Kosek, Milena Stránská, Marie Fenclová, Tomáš Ruml, Libor Vítek, Jana Hajšlová
Statins belong to the major class of hypolipidemic drugs. They act as competitive inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, a rate-limiting enzyme in the cholesterol biosynthetic pathway. This inhibition not only leads to the depletion of cholesterol and its fatty acid esters, but also to the depletion of the intermediates of this metabolic pathway (mainly pyrophosphates), which can play an important role in tumor proliferation. The aim of the current study was to establish a versatile multi-analyte method capable of quantitative determination of various currently-used statins, together with free cholesterol (FC), cholesterol esters (CEs), and some key intermediates of the mevalonate pathway occurring in human serum...
January 31, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28185621/a-new-perspective-of-hollow-fiber-mediated-extraction-bundled-hollow-fiber-array-liquid-phase-microextraction-with-sonication-assisted-desorption-and-liquid-chromatography-tandem-mass-spectrometry-for-determination-of-estrogens-in-aqueous-matrices
#16
Shalene Xue Lin Goh, Hian Kee Lee
A bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) approach has been developed for the ultra-high performance liquid chromatography tandem mass spectrometric determination of estrone, 17β-estradiol, estriol, and 17α-ethinylestradiol. The BHF was dipped in n-octanol to impregnate only the wall pores of the hollow fibers without deliberate loading of extractant solvent in the lumens, before placing it in the sample for extraction. Parameters influencing extraction efficiency, such as number of bundled hollow fibers, type of extraction and desorption solvent, agitation mode, extraction temperature and duration, and the salting out effect were examined...
January 31, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28173925/hydrophilic-interaction-liquid-chromatography-for-dalargin-separation-from-its-structural-analogues-and-side-products
#17
Ayat Abbood, Claire Smadja, Myriam Taverna, Christine Herrenknecht
Retention behaviour of Dalargin and five peptide analogues of Leu-enkephalin, has been extensively studied by hydrophilic interaction liquid chromatography (HILIC) on a bare silica stationary phase (Atlantis(®) HILIC silica). The influence of buffer pH, ionic strength, and organic modifier content on peptide retentions was examined. Variation of organic modifier content (70-90% ACN) shows that, as expected, the most polar peptide, Dalargin, is the most retained. Moreover, at acidic pH, the retention mechanism for all the peptides studied seems to rely, mainly, on adsorption phenomenon...
January 31, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28193467/editorial-to-advances-in-downstream-processing-of-biologics-spectroscopy-an-emerging-process-analytical-technology-by-matthias-r%C3%A3-dt-till-briskot-and-j%C3%A3-rgen-hubbuch
#18
EDITORIAL
https://www.readbyqxmd.com/read/28162237/retention-of-small-molecules-on-polymethacrylate-monolithic-capillary-columns
#19
Michaela Chocholoušková, Martina Komendová, Jiří Urban
In this paper, the concentration of N-isopropylacrylamide in the polymerization mixture has been varied to prepare several polymethacrylate monolithic capillary columns. Polymer monoliths combining N-isopropylacrylamide with zwitterion monomer, as well as various dimethacrylate crosslinking monomers have been prepared and characterized. Uracil, thiourea, phenol, toluene, ethylbenzene, propylbenzene, and butylbenzene have been used to characterize retention of prepared capillary columns in the mobile phases with 40-95% of acetonitrile and at working temperatures ranging from 25 to 60°C...
January 30, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28168978/metal-organic-framework-mixed-matrix-disks-versatile-supports-for-automated-solid-phase-extraction-prior-to-chromatographic-separation
#20
Milad Ghani, Maria Francesca Font Picó, Shima Salehinia, Carlos Palomino Cabello, Fernando Maya, Gloria Berlier, Mohammad Saraji, Víctor Cerdà, Gemma Turnes Palomino
We present for the first time the application of metal-organic framework (MOF) mixed-matrix disks (MMD) for the automated flow-through solid-phase extraction (SPE) of environmental pollutants. Zirconium terephthalate UiO-66 and UiO-66-NH2 MOFs with different size (90, 200 and 300nm) have been incorporated into mechanically stable polyvinylidene difluoride (PVDF) disks. The performance of the MOF-MMDs for automated SPE of seven substituted phenols prior to HPLC analysis has been evaluated using the sequential injection analysis technique...
January 29, 2017: Journal of Chromatography. A
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