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Journal of Chromatography. A

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https://www.readbyqxmd.com/read/28545729/development-of-fast-efficient-and-ecological-method-employing-vortex-assisted-dispersive-liquid-liquid-microextraction-combined-with-fast-gas-chromatography-mass-spectrometry-for-pesticide-residues-analysis-in-alcohol-content-samples
#1
Svetlana Hrouzková, Mária Brišová, Agneša Szarka
A fast, ecological, and efficient method employing vortex-assisted dispersive liquid-liquid microextraction (DLLME) method for isolation and preconcentration of selected endocrine disrupting pesticides from beverages containing some degree of alcohol was developed. The effect of several extraction parameters, such as selection of extractive solvent, its volume and extraction time, the salt addition was investigated. Four different extractive solvents (chloroform, tetrachloroethane, tetrachloromethane and toluene) and their combinations were evaluated for DLLME...
May 17, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28549716/automated-programmable-pressurized-carbonic-acid-eluent-ion-exclusion-chromatography-of-organic-acids
#2
C Phillip Shelor, Purnendu K Dasgupta
Conductometric ion exclusion chromatography of weak acids does not enjoy the same degree of success as its counterpart in suppressed conductometric anion exchange chromatography. Compared to the latter, eluent preparation is not automated. Commonly, a strong acid is used as the eluent leading to a relatively high-detector background and poorer limits of detection. In addition, generally applicable gradient elution has not been possible. We introduce the automated preparation of carbonic acid eluents at concentrations exceeding 0...
May 16, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28533029/determination-of-mineral-oil-aromatic-hydrocarbons-moah-in-edible-oils-and-fats-by-online-liquid-chromatography-gas-chromatography-flame-ionization-detection-lc-gc-fid-evaluation-of-automated-removal-strategies-for-biogenic-olefins
#3
Marco Nestola, Torsten C Schmidt
The determination of mineral oil aromatic hydrocarbons (MOAH) in foodstuffs gained in importance over the last years as carcinogenicity cannot be excluded for certain MOAH. The existence of olefins in foodstuffs, such as edible oils and fats, can be problematic for the determination of MOAH by LC-GC-FID. Removal of these interfering substances by HPLC based on polarity differences is not possible. During gas chromatographic separation heavily overloaded peaks are observed rendering the detection of small mineral oil contaminations almost impossible...
May 16, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28549717/separation-of-alk-en-ylresorcinols-from-rye-bran-with-saturated-monoenoic-dienoic-trienoic-and-hydroxylated-monoenoic-side-chains-using-an-octyl-phase-in-ultra-high-performance-liquid-chromatography-and-their-differentiation-by-tandem-mass-spectrometrie
#4
Benno F Zimmermann, Hannes Patzke, Andreas Schieber
Alkylresorcinols (ARs) occur in bran of cereals and in fruits from the Anacardiaceae family. Their separation by liquid chromatography is challenging, especially in rye (Secale cereale L.) that has a complex AR composition. An octyl phase (C8) with 1.8μm particles was used for the analysis of an acetone extract of rye bran. The ARs were detected by UV at 205 and 275nm and by MS applying selected ion monitoring (SIM) of known and hypothetical m/z values in positive and negative mode. The compounds found were subjected to product ion scans in a triple quadrupole mass spectrometer...
May 15, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28539200/-two-dimensional-molecularly-imprinted-solid-phase-extraction-coupled-with-crystallization-and-high-performance-liquid-chromatography-for-fast-semi-preparative-purification-of-tannins-from-pomegranate-husk-extract
#5
Guangying Sun, Yanfang Liu, Hasanjan Ahat, Aijin Shen, Xinmiao Liang, Xingya Xue, Yuqin Luo, Jian Yang, Zhao-Sheng Liu, Haji Akber Aisa
In this study, "two dimensional" molecularly imprinted solid-phase extraction (2D-MIP-SPE) of semi-preparative grade was constructed to fast purify ellagitannins in pomegranate husk extract with the help of crystallization and reverse-phase liquid chromatgoraphy (RPLC). Ellagic acid and punicalagin imprinted polymers were synthesized in batch mode and two semi-preparative MIP-SPE columns were individually packed. After investigaing "functional complementation", 2D-MIP-SPE was constructed using ellagic acid MIP and punicalagin MIP-SPE as the first and second dimension, respectively...
May 15, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28533030/core-shell-silica-particles-with-dendritic-pore-channels-impregnated-with-zeolite-imidazolate-framework-8-for-high-performance-liquid-chromatography-separation
#6
Qishu Qu, Han Xuan, Kehua Zhang, Xiaoming Chen, Yi Ding, Shaojie Feng, Qin Xu
Metal-organic frameworks (MOFs) have been emerged as promising stationary phases for separations. However, the irregular shapes and wide size distribution of MOF particles have led to the high column backpressure and low column efficiency. We described here a kinetic controlling method to deposit zeolitic imidazolate framework (ZIF-8) onto the pore surface using core-shell silica spheres as support. By varying the volume ratio of N,N-dimethylformamide and methanol, the formation speed of ZIF-8 crystals were greatly suppressed, resulting in the growth of very thin layer (∼3...
May 15, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28549715/direct-residue-analysis-of-systemic-insecticides-and-some-of-their-relevant-metabolites-in-wines-by-liquid-chromatography-mass-spectrometry
#7
J D Berset, S Mermer, A E Robel, V M Walton, M L Chien, J A Field
A direct large volume injection (DI-LVI) high performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS) method was developed and validated for the quantitative determination of 16 systemic insecticides and their main plant metabolites. The assays were conducted on commercial red and white wines made from grapes grown in major wine-producing regions nationally and internationally. Using a 1:20 dilution and an injection volume of 800μL, a limit of quantitation (LOQ) of 1μgL(-1) for all analytes was achieved...
May 13, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28533027/extraction-media-used-in-needle-trap-devices-progress-in-development-and-application
#8
REVIEW
Kamila Kędziora, Wiesław Wasiak
Analysis of trace compounds in complex matrices requires a preliminary step of sample preparation. From among widely used methodologies, microextraction techniques have become increasingly important as they tend towards being environmentally friendly. The needle trap (NT) extraction is a relatively new and promising technique which combines sampling, sample preparation and sample introduction. The core of the needle trap device is a suitable sorbent material packed inside the needle, that determines selectivity and efficiency of the method...
May 12, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28527527/small-scale-separation-of-isoxazole-structurally-related-analogues-by-chiral-supercritical-fluid-chromatography
#9
Yasmine Zehani, Lucas Lemaire, Regis Millet, Emmanuelle Lipka
Chromatographic preparative enantioseparation is now the preferred method to obtain milligram amounts of pure enantiomers in the first step of the development of a therapeutic molecule. Supercritical fluid chromatography has many advantages over liquid chromatography and was therefore chosen for the small scale enantioseparation of four original 3-carboxamido-5-aryl isoxazole molecules, ligands of the CB2 cannabinoid receptors. The preparation of about 10mg of each of the eight enantiomers was achieved successfully on a Chiralpak(®) AD-H (tris-3,5-dimethylphenylcarbamate of amylose) polysaccharide based stationary phase with various percentages of ethanol as a co-solvent, through mixed-stream injections and touching-band approach...
May 12, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28535934/validated-high-performance-anion-exchange-chromatography-with-pulsed-amperometric-detection-method-for-the-determination-of-residual-keratan-sulfate-and-other-glucosamine-impurities-in-sodium-chondroitin-sulfate
#10
Susanna Bottelli, Gianluca Grillo, Edoardo Barindelli, Alessandro Nencioni, Alessandro Di Maria, Tiziano Fossati
An efficient and sensitive analytical method based on high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was devised for the determination of glucosamine (GlcN) in sodium chondroitin sulfate (CS). Glucosamine (GlcN) is intended as marker of residual keratan sulfate (KS) and other impurities generating glucosamine by acidic hydrolyzation. The latter brings CS and KS to their respective monomers. Since GlcN is present only in KS we developed a method that separates GlcN from GalN, the principal hydrolytic product of CS, and then we validated it in order to quantify GlcN...
May 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28533032/design-and-synthesis-of-an-immobilized-metal-affinity-chromatography-and-metal-oxide-affinity-chromatography-hybrid-material-for-improved-phosphopeptide-enrichment
#11
Da-Song Yang, Xi-Ying Ding, Hong-Ping Min, Bo Li, Meng-Xiang Su, Miao-Miao Niu, Bin Di, Fang Yan
Reversible phosphorylation of proteins is one of the most important post-translational modifications, while the detection of phosphopeptides is difficult due to their low abundance and the signal suppression of nonphosphorylated peptides. Therefore, selective enrichment of phosphopeptides from highly complicated mixtures is vital for MS-based phosphoproteome analysis. Despite various strategies have been developed, there is no single method that is capable of providing full coverage of the whole phosphoproteome...
May 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28528682/chemical-fixation-to-arrest-phospholipid-signaling-for-chemical-cytometry
#12
Angela Proctor, Christopher E Sims, Nancy L Allbritton
Chemical cytometry is a powerful tool for measuring biological processes such as enzymatic signaling at the single cell level. Among these technologies, single-cell capillary zone electrophoresis (CZE) has emerged as a powerful tool to assay a wide range of cellular metabolites. However, analysis of dynamic processes within cells remains challenging as signaling pathways are rapidly altered in response to changes in the cellular environment, including cell manipulation and storage. To address these limitations, we describe a method for chemical fixation of cells to stop the cellular reactions to preserve the integrity of key signaling molecules or reporters within the cell and to enable the cell to act as a storage reservoir for the reporter and its metabolites prior to assay by single-cell CZE...
May 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28528681/multilayer-adsorption-in-liquid-chromatography-the-surface-heterogeneity-below-an-adsorbed-multilayer
#13
Krisztián Horváth, Péter Vajda, Attila Felinger
A numerical method was introduced for the estimation of the surface heterogeneity below an adsorbed multilayer of the analyte. The calculation procedure is based on the raw adsorption isotherm data points obtained by frontal analysis experiments. To permit the mapping of the nature of the analyte-surface interaction, a numerical procedure was used to pre-estimate the adsorbate-adsorbate interactions occurring during the adsorption process. The surface heterogeneity estimation was carried out using the affinity-energy distribution calculations with assuming local BET isotherm...
May 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28521953/optimized-selection-of-liquid-chromatography-conditions-for-wide-range-analysis-of-natural-compounds
#14
Aurélie Periat, Davy Guillarme, Jean-Luc Veuthey, Julien Boccard, Sofia Moco, Denis Barron, Alexandre Grand-Guillaume Perrenoud
Plant secondary metabolites are an almost unlimited reservoir of potential bioactive compounds. In view of the wide chemical space covered by natural compounds, their comprehensive analysis requires multiple and complementary approaches. In this study, numerous chromatographic conditions were tested for the analysis of a set of 120 representative natural compounds covering a wide polarity range (18 log P units). The experiments were performed on 59 different conditions involving 29 RPLC and HILIC dedicated stationary phases, as well as more exotic mixed mode columns...
May 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28545731/enzyme-linked-immunoassay-based-on-imprinted-microspheres-for-the-detection-of-sulfamethazine-residue
#15
Dapeng Peng, Zhaozhou Li, Yulian Wang, Zhenli Liu, Feng Sheng, Zonghui Yuan
This study attempts to develop an enzyme-linked immunoassay (ELISA) using a molecularly imprinted polymer (MIP) as an artificial recognition element. The MIP microspheres were prepared using precipitation polymerization with SM2 as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. After the microspheres were coated in microtiter plate wells, the molecular imprinting ELISA (MI-ELISA) method was established based on the direct competition between free SM2 and horseradish peroxidase (HRP)-labelled SM2 in heterogeneous mode...
May 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28533031/enantioseparation-and-optical-rotation-of-flavor-relevant-4-alkyl-branched-fatty-acids
#16
Dorothee Eibler, Walter Vetter
Short chain 4-alkyl-branched fatty acids are character impact compounds of the flavor of sheep and goat milk and meat. Due to their methyl or ethyl branches these volatile fatty acids are chiral, and both enantiomers are characterized by different aroma intensities. Recently, it was found that 4-methyloctanoic acid (4-Me-8:0), 4-ethyloctanoic acid (4-Et-8:0), and 4-methylnonanoic acid (4-Me-9:0) are enantiopure in goat and sheep samples, if present. Here we generated enantiopure or enantioenriched standards from racemates by means of (R)-selective esterification with lipase B and verified that 4-Me-8:0, 4-Et-8:0 and 4-Me-9:0 were (R)-enantiopure in these tissues...
May 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28533028/optimizing-targeted-untargeted-metabolomics-by-automating-gas-chromatography-mass-spectrometry-gc-gc-ms-and-gc-ms-workflows
#17
Albert Robbat, Nicole Kfoury, Eugene Baydakov, Yuriy Gankin
New database building and MS subtraction algorithms have been developed for automated, sequential two-dimensional gas chromatography/mass spectrometry (GC-GC/MS). This paper reports the first use of a database building tool, with full mass spectrum subtraction, that does not rely on high resolution MS data. The software was used to automatically inspect GC-GC/MS data of high elevation tea from Yunnan, China, to build a database of 350 target compounds. The database was then used with spectral deconvolution to identify 285 compounds by GC/MS of the same tea...
May 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28521954/gas-chromatography-mass-spectrometry-strategies-for-the-accurate-and-sensitive-speciation-of-sulfur-dioxide-in-wine
#18
Vanesa Carrascon, Ignacio Ontañón, Mónica Bueno, Vicente Ferreira
Understanding the chemistry of wine oxidation requires the accurate and sensitive quantitative determination of the most important molecular species which SO2 can form. An analytical strategy based in three independent static headspace GC-MS determinations is proposed in order to obtain information about the total, nominally free and truly free levels of SO2. Nominally free forms are directly determined after sample acidulation, total forms require the previous incubation at 100°C, and truly free forms are determined after preconcentration of the headspace of the undisturbed sample in an alkaline solution...
May 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28511933/an-initial-demonstration-of-hierarchically-porous-niobium-alkylphosphonates-coordination-polymers-as-potent-radioanalytical-separation-materials
#19
Kai Lv, Chu-Ting Yang, Jun Han, Sheng Hu, Xiao-Lin Wang
Combining the merits of soft-templating and perchlorate oxidation methods, the first-case investigation of niobium alkylphosphonates has uncovered their unique morphology, backbone composition, thermal behavior and huge potentiality as radioanalytical separation materials. These hierarchically porous solids are random aggregates of densely stacked nanolayers perforated with worm-like holes or vesicular voids, manifesting the massif-, tower-like "polymer brush" elevated up to ∼150nm driven by the minimal surface free energy principle...
May 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28511932/determination-of-piperidinium-ionic-liquid-cations-in-environmental-water-samples-by-solid-phase-extraction-and-hydrophilic-interaction-liquid-chromatography
#20
Zi-Qiang Fan, Hong Yu
This paper presents a novel analytical method for the determination of piperidinium ionic liquid cations in environmental water by hydrophilic interaction liquid chromatography and solid-phase extraction technology. The left standing, centrifuged and filtered river water samples were first purified and concentrated through the C18 solid phase extraction column, and eluted with 0.02mol/L hydrochloric acid prepared in methanol and deionized water (80/20, v/v). Then the eluents were analyzed by a hydrophilic column combined with 0...
May 8, 2017: Journal of Chromatography. A
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