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Journal of Chromatography. A

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https://www.readbyqxmd.com/read/28343686/analysis-of-essential-oils-and-fragrances-with-a-new-generation-of-highly-inert-gas-chromatographic-columns-coated-with-ionic-liquids
#1
Cecilia Cagliero, Carlo Bicchi, Chiara Cordero, Erica Liberto, Patrizia Rubiolo, Barbara Sgorbini
In the fields of essential oils and fragrances, samples often consist of mixtures of compounds with similar structural and physical characteristics (e.g. mono- and sesquiterpenoids), whose correct identification closely depends on the synergic combination of chromatographic and mass spectral data. This sample complexity means that new GC stationary phases with different selectivities are continually being investigated. Ionic liquids (ILs) are of great interest as GC stationary phases in this field because of their selectivity (significantly different than that of currently phases) and their high temperature stability...
March 18, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28342584/dispersive-liquid-liquid-microextraction-and-injection-port-derivatization-for-the-determination-of-free-lipophilic-compounds-in-fruit-juices-by-gas-chromatography-mass-spectrometry
#2
Alexis Marsol-Vall, Mercè Balcells, Jordi Eras, Ramon Canela-Garayoa
A method consisting of dispersive liquid-liquid microextraction (DLLME) followed by injection-port derivatization and gas chromatography-mass spectrometry (GC-MS) for the analysis of free lipophilic compounds in fruit juices is described. The method allows the analysis of several classes of lipophilic compounds, such as fatty acids, fatty alcohols, phytosterols and triterpenes. The chromatographic separation of the compounds was achieved in a chromatographic run of 25.5min. The best conditions for the dispersive liquid-liquid microextraction were 100μL of CHCl3 in 1mL of acetone...
March 18, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28342583/affinity-chromatographic-methodologies-based-on-immobilized-voltage-dependent-anion-channel-isoform-1-and-application-in-protein-ligand-interaction-analysis-and-bioactive-compounds-screening-from-traditional-medicine
#3
Qian Li, Pan Qiao, Xiu Chen, Jing Wang, Liujiao Bian, Xiaohui Zheng
Voltage dependent anion channel isoform 1 (VDAC-1) serves as an attractive target of anti-cancer drugs by mediating the entry and exit of metabolites between cytoplasm and mitochondria. This work reports on the preparation of a VDAC-1-based bioaffinity chromatographic stationary phase by linking the protein on lecithin modified microspheres. An assay of chromatographic methods including frontal analysis, zonal elution, injection dependent analysis and nonlinear chromatography were utilized to investigate the bindings of ATP, NADH and NADPH to VDAC-1...
March 18, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28341433/minimizing-the-impact-of-joule-heating-as-a-prerequisite-for-the-reliable-analysis-of-metal-protein-complexes-by-capillary-electrophoresis
#4
Paweł Mateusz Nowak, Klaudyna Śpiewak, Michał Woźniakiewicz, Paweł Kościelniak
Herein we report on a drastic release of metal ions from the Fe-bound transferrin, and Fe- or Mn-bound lactoferrin, observed upon the increase in the separation voltage during CE-based analysis. To verify whether this process is caused directly by electric field, we developed an Isothermal Voltage Increase approach (IVI), which is the extension of methods reported by Krylov et al. IVI ensures isothermal conditions while increasing separation voltage by a hydrodynamic pushing of the injected sample to the actively cooled capillary section, combined with a rationale choice of cooling temperature, dependent on the value of current...
March 18, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28341432/development-validation-and-evaluation-of-an-analytical-method-for-the-determination-of-monomeric-and-oligomeric-procyanidins-in-apple-extracts
#5
Wendy J Hollands, Stefan Voorspoels, Griet Jacobs, Kjersti Aaby, Ane Meisland, Rocio Garcia-Villalba, Francisco Tomas-Barberan, Mariusz K Piskula, Deborah Mawson, Irena Vovk, Paul W Needs, Paul A Kroon
There is a lack of data for individual oligomeric procyanidins in apples and apple extracts. Our aim was to develop, validate and evaluate an analytical method for the separation, identification and quantification of monomeric and oligomeric flavanols in apple extracts. To achieve this, we prepared two types of flavanol extracts from freeze-dried apples; one was an epicatechin-rich extract containing ∼30% (w/w) monomeric (-)-epicatechin which also contained oligomeric procyanidins (Extract A), the second was an oligomeric procyanidin-rich extract depleted of epicatechin (Extract B)...
March 18, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28330782/preparative-two-dimensional-separations-involving-liquid-liquid-chromatography
#6
Léa Marlot, Karine Faure
The increasing performances of analytical techniques, especially two-dimensional liquid chromatography hyphenated with highly sensitive detectors, allow discovery of new targeted compounds in highly complex samples, whether biomarkers in environmental effluents, natural metabolomes in natural products or unknown impurities in synthetic chemical process. While structural identification can usually be achieved through mass spectrometry and databases, it can be useful to confirm the potential structure via NMR analysis and/or to obtain standard reference material for quantitative purposes, incentive for the production of μg to mg of new target compounds...
March 18, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28343687/multiple-simultaneous-independent-gradients-for-a-versatile-multidimensional-liquid-chromatography-part-ii-application-2-computer-controlled-ph-gradients-in-the-presence-of-urea-provide-improved-separation-of-proteins-stability-influenced-anion-and-cation-exchange
#7
Allen G Hirsh, Latchezar I Tsonev
This paper details the use of a method of creating controlled pH gradients (pISep) to improve the separation of protein isoforms on ion exchange (IEX) stationary phases in the presence of various isocratic levels of urea. The pISep technology enables the development of computer controlled pH gradients on both cationic (CEX) and anionic (AEX) IEX stationary phases over the very wide pH range from 2 to 12. In pISep, titration curves generated by proportional mixing of the acidic and basic pISep working buffers alone, or in the presence of non-buffering solutes such as the neutral salt NaCl (0-1M), polar organics such as urea (0-8M) or acetonitrile (0-80 Vol%), can be fitted with high fidelity using high order polynomials which, in turn allows construction of a mathematical manifold %A (% acidic pISep buffer) vs...
March 16, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28342582/simultaneous-determination-of-nitrated-and-oligomerized-proteins-by-size-exclusion-high-performance-liquid-chromatography-coupled-to-photodiode-array-detection
#8
Fobang Liu, Kathrin Reinmuth-Selzle, Senchao Lai, Michael G Weller, Ulrich Pöschl, Christopher J Kampf
Chemical modifications such as nitration and cross-linking may enhance the allergenic potential of proteins. The kinetics and mechanisms of the underlying chemical processes, however, are not yet well understood. Here, we present a size-exclusion chromatography/spectrophotometry method (SEC-HPLC-DAD) that allows a simultaneous detection of mono-, di-, tri-, and higher protein oligomers, as well as their individual nitration degrees (NDs). The ND results of proteins from this new method agree well with the results from an alternative well-established method, for the analysis of tetranitromethane (TNM)- and nitrogen dioxide and ozone (NO2/O3)-nitrated protein samples...
March 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28336138/preparation-of-an-epitope-imprinted-polymer-with-antibody-like-selectivity-for-beta2-microglobulin-and-application-in-serum-sample-analysis-with-a-facile-method-of-on-line-solid-phase-extraction-coupling-with-high-performance-liquid-chromatography
#9
Fangfang Yang, Dandan Deng, Xiangchao Dong, Shen Lin
Molecularly imprinted polymers (MIPs) for protein recognition have great application potential in the biological analysis. However, preparation of protein imprinted polymer is still facing challenge. Beta2-microglobulin (β2m) is a protein biomarker that can be used in diagnosis of different diseases. In this research, a novel MIP with ability of β2m recognition has been developed by epitope and surface-confined imprinting approaches. A peptide with sequence of MIQRTPKIQ was selected as template. A strategy of combination of hierarchical imprinting and template immobilization was employed in the β2m-MIP synthesis...
March 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28325490/development-and-application-of-a-new-in-line-coupling-of-a-miniaturized-boronate-affinity-monolithic-column-with-capillary-zone-electrophoresis-for-the-selective-enrichment-and-analysis-of-cis-diol-containing-compounds
#10
Maria Betzabeth Espina-Benitez, Jérôme Randon, Claire Demesmay, Vincent Dugas
An integrated, miniaturized and fully automated system was developed for the analysis (preconcentration/purification, separation and detection) of cis-diol containing molecules in complex matrices. This innovative in-line coupling system was achieved via the in-situ and localized synthesis of a short segment of silica-based monolith at the inlet of a 75-μm inner diameter fused silica capillary. The monolithic segment was locally functionalized with an acrylamide derivative of phenylboronic acid by free radical photopolymerization within 10min of irradiation time...
March 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28343685/evaluation-of-sources-of-irreproducibility-of-retention-indices-under-programmed-temperature-gas-chromatography-conditions
#11
Liejun Wu, Ii Kyu Cho, Yanjie Li, Guangxiang Zhang, Qing X Li
Retention index under the programmed temperature gas chromatography (PTGC) conditions (I(T)) is widely accepted despite of its unsatisfactory reproducibility. Effects of heating rate (rT), stationary liquid film thickness (df), inlet pressure (pi), initial temperature (To) and polarity of stationary phase (sp) on I(T) reproducibility were studied in the present work. We found that excellent reproducibility and regularity of I(T) values are obtainable at conditions of relatively low To and relatively high rT and pi, as well as use of quality thick-film column under an operation in a single-retention behavior region (i...
March 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28325491/determination-of-short-chain-chlorinated-paraffins-in-water-by-stir-bar-sorptive-extraction-thermal-desorption-gas-chromatography-triple-quadrupole-tandem-mass-spectrometry
#12
P Tölgyessy, S Nagyová, M Sládkovičová
A simple, robust, sensitive and environment friendly method for the determination of short chain chlorinated paraffins (SCCPs) in water using stir bar sorptive extraction (SBSE) coupled to thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry (TD-GC-QqQ-MS/MS) was developed. SBSE was performed using 100mL of water sample, 20mL of methanol as a modifier, and a commercial sorptive stir bar (with 10mm×0.5mm PDMS layer) during extraction period of 16h. After extraction, the sorptive stir bar was thermally desorbed and online analysed by GC-MS/MS...
March 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28320536/retention-models-and-interaction-mechanisms-of-benzene-and-other-aromatic-molecules-with-an-amylose-based-sorbent
#13
Han-Yu Hsieh, Shyuan-Guey Wu, Hung-Wei Tsui
Stoichiometric displacement models have been widely used for understanding the adsorption mechanisms of solutes in chromatography systems. Such models are used for interpreting plots of solute retention factor versus concentrations of polar modifier in an inert solvent. However, these models often assume that dispersion forces are negligible and they are unable to account for solutes with significant aromatic interactions. In this study, a systematic investigation of the relationship between retention behavior and aromatic groups was performed using five simple aromatic molecules-benzene, naphthalene, mesitylene, durene, and toluene-with a commercially available amylose tris(3,5-dimethylphenylcarbamate)-based sorbent...
March 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28320535/optimization-of-selective-pressurized-liquid-extraction-of-organic-pollutants-in-placenta-to-evaluate-prenatal-exposure
#14
REVIEW
Tania Fernández-Cruz, Elena Martínez-Carballo, Jesús Simal-Gándara
The early exposure to organic pollutants (OPs) related to dietary habit or environmental exposure is a concern of growing interest in environmental health. When OPs enter the body, they can accumulate in fatty tissue and even travel through the bloodstream being able to cross the placenta and reach the fetus through the substance exchange between the mother and the child. Epidemiologic and clinical data affirm that these chemicals increase the risk of adverse effects during childhood. This article reviews and addresses one of the most relevant analytical methods for determining OPs in placenta...
March 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28336137/an-ultra-sensitive-method-for-the-analysis-of-perfluorinated-alkyl-acids-in-drinking-water-using-a-column-switching-high-performance-liquid-chromatography-tandem-mass-spectrometry
#15
Kavitha Dasu, Shoji F Nakayama, Mitsuha Yoshikane, Marc A Mills, J Michael Wright, Shelley Ehrlich
In epidemiological research, it has become increasingly important to assess subjects' exposure to different classes of chemicals in multiple environmental media. It is a common practice to aliquot limited volumes of samples into smaller quantities for specific trace level chemical analyses. A novel method was developed for the determination of 14 perfluorinated alkyl acids (PFAAs) in small volumes (10mL) of drinking water using off-line solid phase extraction (SPE) pre-treatment followed by on-line pre-concentration on a WAX column before analysis on column-switching high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS)...
March 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28320534/ionic-liquid-regenerated-macroporous-cellulose-monolith-fabrication-characterization-and-its-protein-chromatography
#16
Kaifeng Du
Macroporous cellulose monolith as chromatographic support was successfully fabricated from an ionic liquid dissolved cellulose solution by an emulsification method and followed by the cross-linking reaction and DEAE modification. With the physical characterization, the cellulose monolith featured by both the interconnected macropores in range of 0.5-2.5μm and the diffusion pores centered at about 10nm. Given the bimodal pore system, the monolith possessed the specific surface area of 36.4m(2)g(-1) and the column permeability of about 7...
March 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28318568/multiresidue-analysis-of-24-water-framework-directive-priority-substances-by-on-line-solid-phase-extraction-liquid-chromatography-tandem-mass-spectrometry-in-environmental-waters
#17
Adrià Rubirola, Mª Rosa Boleda, Mª Teresa Galceran
This paper reports the development of a fully multiresidue and automated on-line solid phase extraction (SPE) - liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of 24 priority substances (PS) belonging to different classes (pesticides, hormones or pharmaceuticals) included in the Directive 2013/39/UE and the recent Watch List (Decision 2015/495) in water samples (drinking water, surface water, and effluent wastewaters). LC-MS/MS conditions and on-line SPE parameters such as sorbent type, sample and wash volumes were optimized...
March 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28314523/detection-of-anabolic-and-androgenic-steroids-and-or-their-esters-in-horse-hair-using-ultra-high-performance-liquid-chromatography-high-resolution-mass-spectrometry
#18
Karen Y Kwok, Timmy L S Choi, Wai Him Kwok, Jenny K Y Wong, Terence S M Wan
Anabolic and androgenic steroids (AASs) are a class of prohibited substances banned in horseracing at all times. The common approach for controlling the misuse of AASs in equine sports is by detecting the presence of AASs and/or their metabolites in urine and blood samples using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). This approach, however, often falls short as the duration of effect for many AASs are longer than their detection time in both urine and blood...
March 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28285711/modelling-cpc-separation-behavior-to-characterize-influencing-hydrodynamic-effects-on-separation-efficiency
#19
C Schwienheer, J Krause, G Schembecker, J Merz
In addition to the selection or adjustment of phase systems to gain a suitable partition coefficient for the target molecule, the separation efficiency in centrifugal partition chromatography (CPC) is strongly influenced by the hydrodynamic interactions of the mobile and the stationary phase in the chambers. Thus, the hydrodynamic interactions must be investigated and understood in order to enhance a CPC separation run. Different hydrodynamic effects like mass transfer, back mixing and the non-ideal behavior of stationary phase, which cannot be determined directly, are known, but quantifying these effects and their influence on separation performance is barely achieved...
March 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28318566/automated-dispersive-liquid-liquid-microextraction-coupled-to-high-performance-liquid-chromatography-cold-vapour-atomic-fluorescence-spectroscopy-for-the-determination-of-mercury-species-in-natural-water-samples
#20
Yao-Min Liu, Feng-Ping Zhang, Bao-Yu Jiao, Jin-Yu Rao, Geng Leng
An automated, home-constructed, and low cost dispersive liquid-liquid microextraction (DLLME) device that directly coupled to a high performance liquid chromatography (HPLC) - cold vapour atomic fluorescence spectroscopy (CVAFS) system was designed and developed for the determination of trace concentrations of methylmercury (MeHg(+)), ethylmercury (EtHg(+)) and inorganic mercury (Hg(2+)) in natural waters. With a simple, miniaturized and efficient automated DLLME system, nanogram amounts of these mercury species were extracted from natural water samples and injected into a hyphenated HPLC-CVAFS for quantification...
March 4, 2017: Journal of Chromatography. A
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