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Journal of Chromatography. A

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https://www.readbyqxmd.com/read/28818329/influence-of-different-packing-methods-on-the-hydrodynamic-stability-of-chromatography-columns
#1
M Dorn, F Eschbach, D Hekmat, D Weuster-Botz
It is well known that packing non-uniformity may cause peak asymmetry and limit the performance of packed-bed chromatographic columns. However, understanding of the reasons leading to packing non-uniformity is still limited. Therefore, the effect of different column packing methods, i.e. dynamic axial compression (DAC), flow packing, and combinations of both on the hydrodynamic packing heterogeneity and stability of packings composed of polymer-based compressible porous resins with a mean diameter of 90μm was investigated experimentally as well as in-silico...
August 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28818327/preparation-of-molecularly-imprinted-polymers-for-warfarin-and-coumachlor-by-multi-step-swelling-and-polymerization-method-and-their-imprinting-effects
#2
Yukari Nakamura, Shizuka Masumoto, Arisa Kubo, Hisami Matsunaga, Jun Haginaka
Monodisperse molecularly imprinted polymers (MIPs) for warfarin (WF) and coumachlor (CC), MIPWF and MIPCC, respectively, were prepared using 4-vinylpyridine (4-VPY) as a functional monomer and ethylene glycole dimethacrylate (EDMA) as a crosslinker by multi-step swelling and polymerization. Six kinds of MIPWF, MIPWF1 - MIPWF6, were prepared varying the concentrations of WF and 4-VPY, while maintaining the EDMA concentration constant, and their retention and molecular recognition properties were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase in LC...
August 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28807549/a-multiplexed-microfluidic-toolbox-for-the-rapid-optimization-of-affinity-driven-partition-in-aqueous-two-phase-systems
#3
Eduardo J S Bras, Ruben R G Soares, Ana M Azevedo, Pedro Fernandes, Miguel Arévalo-Rodríguez, Virginia Chu, João P Conde, M Raquel Aires-Barros
Antibodies and other protein products such as interferons and cytokines are biopharmaceuticals of critical importance which, in order to be safely administered, have to be thoroughly purified in a cost effective and efficient manner. The use of aqueous two-phase extraction (ATPE) is a viable option for this purification, but these systems are difficult to model and optimization procedures require lengthy and expensive screening processes. Here, a methodology for the rapid screening of antibody extraction conditions using a microfluidic channel-based toolbox is presented...
August 5, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28803648/automated-multi-filtration-cleanup-with-nitrogen-enriched-activated-carbon-material-as-pesticide-multi-residue-analysis-method-in-representative-crop-commodities
#4
Yuhong Qin, Jingru Zhang, Yifan Li, Qiuxiao Wang, Yangliu Wu, Lanshu Xu, Xiaojuan Jin, Canping Pan
An automated multi-filtration cleanup (Auto m-FC) method with nitrogen-enriched activated carbon material based on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts was developed. It was applied to pesticide multi-residue analysis in six representative crop commodities. The automatic device was aimed to improve the cleanup efficiency and reduce manual operation workload in cleanup step. By controlling extracts volume, flow rate and Auto m-FC cycles, the device could finish cleanup process accurately...
August 5, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28803646/effect-of-solvent-composition-on-the-van-t-hoff-enthalpic-curve-using-amylose-3-5-dichlorophenylcarbamate-based-sorbent
#5
Ang-Yeh Lin, Kai-Tse Cheng, Sin-Chang Chen, Hung-Wei Tsui
Van't Hoff plots have been widely used for investigating the thermodynamic properties of adsorption processes in various chromatography systems. By measuring the retention factor k over a certain temperature range, the plot of ln k versus 1/T often yields a straight line with a slope of -ΔHvH(0)/R. Although this method provides information on adsorption enthalpy changes, its theoretical basis does not account for the effect of the solvent. In this paper, the relationship between apparent enthalpy changes determined directly from van't Hoff plots and solvent modifier concentrations is systematically investigated using three simple solutes-tetrahydrofuran, acetone, and tert-butanol-in an n-hexane-methyl tert-butyl ether (MTBE) mobile phase with an amylose 3,5-dichlorophenylcarbamate-based sorbent...
August 4, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28803650/lipid-determination-in-bone-marrow-and-mineralized-bone-tissue-from-sample-preparation-to-improved-high-performance-thin-layer-and-liquid-chromatographic-approaches
#6
Alexandrine During
In view of their key roles in the bone physiology (e.g., in the biomineralization process) and their potential implication in bone pathologies, an approach to study lipids in situ is needed. The aim of the present paper is to propose an original procedure to characterize lipids in both bone marrow (BM) and mineralized tissue (MT) compartments, taking into consideration sample preparation, lipid extraction and analytical issues, when using small sample size (≤ 0.5g of rat femurs). The potential contamination of the MT by marrow lipids and the poor accessibility of certain lipids from the MT - two major issues in bone handling - were taking care, respectively by performing two cleaning steps after BM removal and by adding a demineralization step to the overall lipid extraction protocol...
August 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28803647/determination-of-selected-endogenous-anabolic-androgenic-steroids-and-ratios-in-urine-by-ultra-high-performance-liquid-chromatography-tandem-mass-spectrometry-and-isotope-pattern-deconvolution
#7
J Pitarch-Motellón, J V Sancho, M Ibáñez, O Pozo, A F Roig-Navarro
An isotope dilution mass spectrometry (IDMS) method for the determination of selected endogenous anabolic androgenic steroids (EAAS) in urine by UHPLC-MS/MS has been developed using the isotope pattern deconvolution (IPD) mathematical tool. The method has been successfully validated for testosterone, epitestosterone, androsterone and etiocholanolone, employing their respective deuterated analogs using two certified reference materials (CRM). Accuracy was evaluated as recovery of the certified values and ranged from 75% to 108%...
August 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28803645/liquid-chromatography-quadrupole-orbitrap-mass-spectrometry-method-for-selected-pharmaceuticals-in-water-samples
#8
Jalal T Althakafy, Chadin Kulsing, Michael R Grace, Philip J Marriott
This study developed an analytical approach for sub-ppb level detection and confirmation of 13 pharmaceuticals and personal care products (PPCPs) in water samples using ultra high pressure liquid chromatography hyphenated with a quadrupole Orbitrap mass spectrometer (UHPLC- Q-Orbitrap-MS). Sample preparation was performed by using solid phase extraction (SPE) employing hydrophilic-lipophilic balance cartridges, with elution of sorbed analytes using methanol. Acceptable automatic gain control (AGC) target and maximum injection time (IT) were 1×10(6) and 200ms, respectively, resulting in a mass accuracy <2ppm...
August 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28802526/sodium-hyaluronate-functionalized-urea-formaldehyde-monolithic-column-for-hydrophilic-in-tube-solid-phase-microextraction-of-melamine
#9
Jiabin Wang, Nan Jiang, Zhengmiao Cai, Wenbang Li, Jianhua Li, Xucong Lin, Zenghong Xie, Lijun You, Qiqing Zhang
A novel sodium hyaluronate-functionalized urea-formaldehyde (UF) monolithic column has been developed by in-situ polycondensation of urea, formaldehyde and sodium hyaluronate (HA). HA plays both the roles of crosslinking and hydrophilic functionalization. The preparation factors including different molecular weights of HA and different amounts of HA were optimized, and then a uniform monolith with satisfactory permeability and hydrophilic binding capacity was obtained. Due to the excellent hydrophilicity of HA, HA-functionalized UF monolith showed higher hydrophilic extraction efficiency than UF monolith, and was applied for hydrophilic in-tube solid-phase microextraction (SPME) of melamine (MEL)...
August 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28811101/chiral-stationary-phase-optimized-selectivity-liquid-chromatography-a-strategy-for-the-separation-of-chiral-isomers
#10
Ravindra Suryakant Hegade, Maarten De Beer, Frederic Lynen
Chiral Stationary-Phase Optimized Selectivity Liquid Chromatography (SOSLC) is proposed as a tool to optimally separate mixtures of enantiomers on a set of commercially available coupled chiral columns. This approach allows for the prediction of the separation profiles on any possible combination of the chiral stationary phases based on a limited number of preliminary analyses, followed by automated selection of the optimal column combination. Both the isocratic and gradient SOSLC approach were implemented for prediction of the retention times for a mixture of 4 chiral pairs on all possible combinations of the 5 commercial chiral columns...
August 2, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28802527/application-of-an-immobilized-ionic-liquid-for-the-passive-sampling-of-perfluorinated-substances-in-water
#11
Lei Wang, Xinying Gong, Ruonan Wang, Zhiwei Gan, Yuan Lu, Hongwen Sun
Ionic liquids have been used to efficiently extract a wide range of polar and nonpolar organic contaminants from water. In this study, imidazole ionic liquids immobilized on silica gel were synthesized through a chemical bonding method, and the immobilized dodecylimidazolium ionic liquid was selected as the receiving phase material in a POCIS (polar organic chemical integrative sampler) like passive sampler to monitor five perfluoroalkyl substances (PFASs) in water. Twenty-one days of integrative accumulation was conducted in laboratory scale experiments, and the accumulated PFASs in the samplers were eluted and analyzed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS)...
August 2, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28802524/characterization-of-chromatographic-peaks-using-the-linearly-modified-gaussian-lmg-model-comparison-with-the-bi-gaussian-and-the-foley-and-dorsey-approaches
#12
J J Baeza-Baeza, M C García-Alvarez-Coque
To characterize column performance in liquid chromatography, several parameters must be obtained from experimental data. These parameters can be computed through the numerical integration of the net signal to calculate the moments after subtraction of the baseline. This requires the establishment of the peak integration limits. The whole process introduces significant uncertainty. For this reason, several alternative procedures have been proposed to measure the area, mean time and variance, based on the assumption that the chromatographic peak can be described with a mathematical function...
August 2, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28801042/triacylglycerols-tags-in-edible-oils-determination-characterization-quantitation-chemometric-approach-and-evaluation-of-adulterations
#13
REVIEW
Serena Indelicato, David Bongiorno, Rosa Pitonzo, Vita Di Stefano, Valentina Calabrese, Sergio Indelicato, Giuseppe Avellone
Vegetable oils are a dietary source of lipids that constitute an essential component of a healthy diet. The commonly used vegetable oils differ significantly for their triacylglycerol (TAG) profile. TAGs represent the principal components of oils and may contain different fatty acids (FA) esterified with glycerol leading to several positional isomers. To differentiate individual TAGs species in edible oils, advanced analysis systems and innovative methods are therefore required. TAGs can be considered as good fingerprints for quality control and many studies have been performed to develop rapid and low cost analytical methods to determinate the authenticity, origin and eventually evidence frauds or adulterations...
August 2, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28818326/dual-wavelength-led-based-uv-absorption-detector-for-nano-flow-capillary-liquid-chromatography
#14
Xiaofeng Xie, Luke T Tolley, Thy X Truong, H Dennis Tolley, Paul B Farnsworth, Milton L Lee
The design of a miniaturized LED-based UV-absorption detector was significantly improved for on-column nanoflow LC. The detector measures approximately 27mm×24mm×10mm and weighs only 30g. Detection limits down to the nanomolar range and linearity across 3 orders of magnitude were obtained using sodium anthraquinone-2-sulfonate as a test analyte. Using two miniaturized detectors, a dual-detector system was assembled containing 255nm and 275nm LEDs with only 216nL volume between the detectors A 100μm slit was used for on-column detection with a 150μm i...
August 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28811099/understanding-operational-system-differences-for-transfer-of-miniaturized-chromatography-column-data-using-simulations
#15
William R Keller, Steven T Evans, Gisela Ferreira, David Robbins, Steven M Cramer
In this paper, a simulation tool was employed to identify and appropriately incorporate differences between MiniColumns and benchtop column systems. It was first demonstrated that including multi-step gradients and fraction collection into the simulations resulted in improved agreement between simulated and experimental linear gradient profiles as well as calculated first moments in the MiniColumn experiments. Step elution experiments of binary mixtures (a monoclonal antibody and one of three model proteins) were then carried out to examine comparability of the MiniColumns to the benchtop system...
August 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28807547/gas-chromatography-mass-spectrometry-and-high-performance-liquid-chromatography-diode-array-detection-for-dating-of-paper-ink
#16
Oscar Díaz-Santana, Daura Vega-Moreno, Francisco Conde-Hardisson
An extraction and determination method is shown for the analysis of dyes and solvents present in two types of ballpoint pen inks that are deposited onto paper. Ink extracts are analysed using a combination of gas chromatography with mass spectrometry (GC-MS), and high-pressure liquid chromatography with photodiode array detection (HPLC-DAD), within a single sample extraction procedure. Seventeen solvents and thirteen dyes contained in two Montblanc(®) inks (black and blue) were monitored for 45 months at monthly intervals, in order to determine variations in the concentrations of the compounds over time...
August 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28803649/root-cause-investigation-of-deviations-in-protein-chromatography-based-on-mechanistic-models-and-artificial-neural-networks
#17
Gang Wang, Till Briskot, Tobias Hahn, Pascal Baumann, Jürgen Hubbuch
In protein chromatography, process variations, such as aging of column or process errors, can result in deviations of the product and impurity levels. Consequently, the process performance described by purity, yield, or production rate may decrease. Based on visual inspection of the UV signal, it is hard to identify the source of the error and almost unfeasible to determine the quantity of deviation. The problem becomes even more pronounced, if multiple root causes of the deviation are interconnected and lead to an observable deviation...
August 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28797664/investigation-of-zinc-oxide-particles-in-cosmetic-products-by-means-of-centrifugal-and-asymmetrical-flow-field-flow-fractionation
#18
Vanessa Sogne, Florian Meier, Thorsten Klein, Catia Contado
The dimensional characterization of insoluble, inorganic particles, such as zinc oxide ZnO, dispersed in cosmetic or pharmaceutical formulations, is of great interest considering the current need of declaring the possible presence of nanomaterials on the label of commercial products. This work compares the separation abilities of Centrifugal- and Asymmetrical Flow Field-Flow Fractionation techniques (CF3 and AF4, respectively), equipped with UV-vis, MALS and DLS detectors, in size sorting ZnO particles, both as pristine powders and after their extraction from cosmetic matrices...
August 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28789800/rapid-ultrasonic-and-microwave-assisted-micellar-extraction-of-zingiberone-shogaol-and-gingerols-from-gingers-using-biosurfactants
#19
Li-Qing Peng, Jun Cao, Li-Jing Du, Qi-Dong Zhang, Jing-Jing Xu, Yu-Bo Chen, Yu-Ting Shi, Rong-Rong Li
Two kinds of extraction methods ultrasonic-assisted micellar extraction (UAME) and microwave-assisted micellar extraction (MAME) coupled with ultra-high performance liquid chromatography with ultraviolet detector (UHPLC-UV) were developed and evaluated for extraction and determination of zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol in Rhizoma Zingiberis and Rhizoma Zingiberis Preparata. A biosurfactant, hyodeoxycholic acid sodium salt, was used in micellar extraction. Several experimental parameters were studied separately by a univariate method...
August 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28801045/mathematical-modelling-and-evaluation-of-performance-of-cuboid-packed-bed-devices-for-chromatographic-separations
#20
Raja Ghosh, Guoqiang Chen
In a recent paper, box-shaped or cuboid packed bed devices have been proposed as alternative to columns for chromatographic separations. We first propose a mathematical model for residence time distribution in such devices. Based on it, we examine factors likely to affect separation performance, and verify the predictions of our mathematical model by conducting tracer experiments. We then compare the performance of two commercial columns with their respective equivalent cuboid packed-bed devices, i.e. containing the same chromatographic media, and having the same bed-height and bed-volume...
July 31, 2017: Journal of Chromatography. A
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