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Journal of Chromatography. A

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https://www.readbyqxmd.com/read/28434714/speed-resolution-advantage-of-turbulent-supercritical-fluid-chromatography-in-open-tubular-columns-ii-theoretical-and-experimental-evidences
#1
Fabrice Gritti, Michael Fogwill
The potential advantage of turbulent supercritical fluid chromatography (TSFC) in open tubular columns (OTC) was evaluated on both theoretical and practical viewpoints. First, the dispersion model derived by Golay in 1958 and recently extended from laminar to turbulent flow regime is used for the predictions of the speed-resolution performance in TSFC. The average dispersion coefficient of matter in the turbulent flow regime was taken from the available experimental data over a range of Reynolds number from 2000 to 6000...
April 19, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28434712/evidence-for-an-imidazoline-by-product-from-glycans-using-tandem-mass-spectrometry
#2
Robert J Duff, Elaine Smith, Wenzhou Li, Szilan Fodor
Herein is reported the separation and identification of a previously unknown imidazoline by-product originating from the fluorescent labeling procedure when applied to enzymatically released N-linked glycans of a human IgG1. The imidazoline by-product was generated via the reductive amination procedure with either sodium cyanoborohydride or 2-picoline borane. Using ultra performance liquid chromatography (UPLC) in conjunction with hydrophilic interaction-based chromatography (HILIC), the 2-aminobenzoic acid (2-AA)-labeled glycans were well-resolved from imidazoline by-products to facilitate direct identification utilizing electrospray ionization mass spectrometry (ESI-MS) with fragmentation...
April 18, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28438316/multiple-modes-of-capillary-electrophoresis-applied-in-peptide-nucleic-acid-related-study
#3
Xiaoqian Wang, Youhao Hu, Feng Qu, Rizwan Ullah Khan
Peptide Nucleic Acid (PNA) is a nucleic acid analogue, whose neutrally charged and hydrophobic backbone makes it more stable in vivo, so it might act as a potentially better protein probe as compared to aptamer. Currently the investigation of PNA and protein interaction is scarce. In this research, multiple modes of capillary electrophoresis were established and applied for PNA characterization and its interaction with ssDNA and protein. A 15-mer PNA having the same nucleobase sequence as 15-mer anti-thrombin DNA aptamer was chosen as PNA model for this study, its pI (7...
April 17, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28434711/validation-of-an-ultra-high-performance-liquid-chromatography-tandem-mass-spectrometry-method-to-quantify-illicit-drug-and-pharmaceutical-residues-in-wastewater-using-accuracy-profile-approach
#4
Cécile Hubert, Martin Roosen, Yves Levi, Sara Karolak
The analysis of biomarkers in wastewater has become a common approach to assess community behavior. This method is an interesting way to estimate illicit drug consumption in a given population: by using a back calculation method, it is therefore possible to quantify the amount of a specific drug used in a community and to assess the consumption variation at different times and locations. Such a method needs reliable analytical data since the determination of a concentration in the ngL(-1) range in a complex matrix is difficult and not easily reproducible...
April 15, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28434715/separation-of-janus-droplets-and-oil-droplets-in-microchannels-by-wall-induced-dielectrophoresis
#5
Mengqi Li, Dongqing Li
The continuous separation of different types of droplets from a mixture is important in industrial and research applications. Currently researches for droplet separation focus on homogeneous emulsion droplets, and there is no study on the separation of heterogeneous droplets. The wall-induced dielectrophoresis, which originates from the non-uniform electrical field around a sphere nearby a planar wall, can be applied to separate dielectric particle and cells. In this work, the continuous separations of oil droplets and the electrically induced Janus droplets (EIJDs) in a microchannel by using the wall-induced dielectrophoresis method were presented...
April 14, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28434713/detection-of-trace-fluoride-in-serum-and-urine-by-online-membrane-based-distillation-coupled-with-ion-chromatography
#6
Chaoyan Lou, Dandan Guo, Nani Wang, Shuchao Wu, Peimin Zhang, Yan Zhu
An online membrane-based distillation (MBD) coupled with ion chromatography (IC) method was proposed for automatic detection of trace fluoride (F(-)) in serum and urine samples. The system consisted of a sample vessel, a lab-made membrane module and an ion chromatograph. Hydrophobic polytetrafluoroethylene (PTFE) hollow fiber membrane was used in MBD which was directly performed in serum and urine samples to eliminate the matrix interferences and enrich fluoride, while enabling automation. The determination of fluoride in biological samples was carried out by IC with suppressed conductometric detection...
April 14, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28434710/shifting-the-paradigm-in-gas-chromatography-mass-spectrometry-pesticide-analysis-using-high-resolution-accurate-mass-spectrometry
#7
S Uclés, A Uclés, A Lozano, M J Martínez Bueno, A R Fernández-Alba
In the last 10 years, the majority of the pesticide food control laboratories moved from GC-MS to GC-MS/MS as the preferred analytical technique to address GC amenable compounds. The main reason for this change was the negative impact on the single stage GC-MS analysis caused by the interference from coeluting matrix compounds. The new development of gas chromatography coupled to high resolution accurate mass spectrometry (GC-HRAMS) provides opportunities to overcome such matrix interferences as a result of its much higher selectivity; allowing laboratories to carry out full-scan analysis covering the most exigent analytical performance criteria...
April 14, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28434709/target-analysis-of-tert-butyldimethylsilyl-derivatives-of-nerve-agent-hydrolysis-products-by-selectable-one-dimensional-or-two-dimensional-gas-chromatography-mass-spectrometry
#8
Yasuo Seto, Masumi Tachikawa, Mieko Kanamori-Kataoka, Kikuo Sasamoto, Nobuo Ochiai
A target analysis method for the sensitive and discriminative determination of the nerve agent hydrolysis products alkyl methylphosphonic acids as their tert-butyldimethylsilyl (TBDMS) derivatives was developed using a combination of selectable one- and two-dimensional ((1)D/(2)D) GC-MS, and applied to the analysis of samples with significant interfering matrices. After sample drying, the alkylmethylphosphonic acids and methylphosphonic acid (MPA) were converted to TBDMS derivatives by addition of N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide with heating, and subjected to (1)D/(2)D GC-MS...
April 13, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28438317/a-novel-chromatographic-approach-to-distinguish-gram-positive-from-gram-negative-bacteria-using-exogenous-volatile-organic-compound-metabolites
#9
Susana Ramírez-Guízar, Hannah Sykes, John D Perry, Edward C Schwalbe, Stephen P Stanforth, Ma Cristina I Perez-Perez, John R Dean
This paper utilized L-alanine aminopeptidase activity as a useful approach to distinguish between Gram-negative and Gram-positive bacteria. This was done using two enzyme substrates, specifically 2-amino-N-phenylpropanamide and 2-amino-N-(4-methylphenyl)propanamide which liberated the volatile compounds aniline and p-toluidine, respectively. Two complementary analytical techniques have been used to identify and quantify the VOCs, specifically static headspace multicapillary column gas chromatography ion mobility spectrometry (SHS-MCC-GC-IMS) and headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS)...
April 12, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28433433/design-selection-and-development-of-cyclic-peptide-ligands-for-human-erythropoietin
#10
William S Kish, Hiroyuki Sachi, Amith D Naik, Matthew K Roach, Benjamin G Bobay, Robert K Blackburn, Stefano Menegatti, Ruben G Carbonell
This work presents the selection and characterization of erythropoietin (EPO)-binding cyclic peptide ligands. The sequences were selected by screening a focused library of cyclic depsipeptides cyclo[(Nα-Ac)Dap(A)-X1-X6-AE], whose structure and amino acid compositions were tailored to mimic the EPO receptor. The sequences identified through library screening were synthesized on chromatographic resin and characterized via binding-and-elution studies against EPO to select a pool of candidate ligands. Sequences with higher hydrophobicity consistently showed stronger binding to EPO, with the exception of FSLLSH, which was noted for its lower hydrophobicity and high EPO binding...
April 12, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28431688/thermal-desorption-gas-chromatographic-methodology-for-the-determination-of-residual-solvents-in-mesoporous-silica
#11
Adissu Alemayehu Asfaw, Kris Wolfs, Ann Van Schepdael, Erwin Adams
In this work, thermal desorption-gas chromatography-flame ionization detection (TD-GC-FID) was adapted to enable the determination of residual solvents (RS) in mesoporous silica (MPSi). MPSi is often utilized in various pharmaceutical formulations or drug delivery systems and the accurate determination of RS is an important part of pharmaceutical quality control. Seven commonly used solvents (methanol, ethanol, acetone, isopropanol, dichloromethane, tetrahydrofuran and hexafluoroisopropanol) were evaluated in combination with 3 types of MPSi having pore sizes of 2-3, 15 and 25nm...
April 12, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28433434/non-conventional-solvents-in-liquid-phase-microextraction-and-aqueous-biphasic-systems
#12
REVIEW
Jiwoo An, María J Trujillo-Rodríguez, Verónica Pino, Jared L Anderson
The development of rapid, convenient, and high throughput sample preparation approaches such as liquid phase microextraction techniques have been continuously developed over the last decade. More recently, significant attention has been given to the replacement of conventional organic solvents used in liquid phase microextraction techniques in order to reduce toxic waste and to improve selectivity and/or extraction efficiency. With these objectives, non-conventional solvents have been explored in liquid phase microextraction and aqueous biphasic systems...
April 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28420529/separation-of-antibody-monomer-dimer-mixtures-by-frontal-analysis
#13
Jason M Reck, Timothy M Pabst, Alan K Hunter, Giorgio Carta
The removal of aggregates, particularly soluble dimers, from monoclonal antibodies (mAbs) remains a persistent challenge in downstream processing. In this work, we have examined the separation of an antibody monomer from its dimer on the cation exchange resin Nuvia HR-S (Bio-Rad Laboratories) using frontal analysis. In this process, a mixture of monomer and dimer is continuously fed to the column under conditions where the mixture is favorably bound, resulting in two breakthrough fronts whose monomer and dimer compositions are determined by the multi-component equilibrium and kinetics of the system...
April 10, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28420530/rapid-determination-of-the-various-native-forms-of-vitamin-b6-and-b2-in-cow-s-milk-using-ultra-high-performance-liquid-chromatography
#14
A Schmidt, M G Schreiner, H K Mayer
As the formation of pyridoxal phosphate, the active cofactor of vitamin B6, is dependent on riboflavin 5-phosphate, we propose a fast and simple ultra-high performance liquid chromatography method for the simultaneous determination of the native B6 vitamers pyridoxal, pyridoxine, pyridoxamine, their mono phosphorus esters and 4-pyridoxic acid as well as vitamin B2 as riboflavin and its phosphorus ester riboflavin 5-phosphate in milk. Separation was achieved under 6.0min by reversed-phase and pH gradient elution...
April 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28416218/dummy-molecularly-imprinted-microbeads-as-solid-phase-extraction-material-for-selective-determination-of-phthalate-esters-in-water
#15
Elif Tümay Özer, Bilgen Osman, Tuğçe Yazıcı
The aim of this study was to investigate the usability of newly synthesized dummy molecularly imprinted microbeads (DMIMs) as a solid phase extraction (SPE) material to determine six phthalate esters (PEs) in water by GC-MS analysis. Diethyl phthalate (DEP) was used as a dummy template to prepare poly(ethylene glycol dimethacrylate N-methacryloyl-l-tryptophan methyl ester) [PEMATrp)] DMIMs by using suspension polymerization. The PEMATrp DMIMs were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM)...
April 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28433435/fabric-phase-sorptive-extraction-as-a-reliable-tool-for-rapid-screening-and-detection-of-freshness-markers-in-oranges
#16
M Aznar, S Úbeda, C Nerin, A Kabir, K G Furton
A simple, fast and sensitive analyte extraction method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-QTOF-MS) analysis was developed for the analysis of 12 volatile compounds that represent most of the principal chemical families possessing different polarities and volatilities. Five FPSE media coated with different sol-gel sorbent chemistries having different polarities and selectivities were studied: long chain poly(dimethylsiloxane) (PDMS), short chain poly(tetrahydrofuran) (PTHF), Carbowax 20M (CW20M), short chain poly(dimethyl siloxane) (SC PDMS) and polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (PEG-PPG-PEG)...
April 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28431687/a-rapid-impregnation-method-for-loading-desired-amounts-of-extractant-on-prepacked-reversed-phase-columns-for-high-performance-liquid-chromatographic-separation-of-metal-ions
#17
Muhammad Ramzan, Dejene Kifle, Grethe Wibetoe
A time-efficient impregnation method for loading extractant onto reversed-phase columns was developed, using di-(2-ethylhexyl) phosphoric acid (HDEHP) as a model extractant. The optimal loading conditions for the impregnation process of a standard analytical scale column was achieved by dissolving an appropriate amount of HDEHP (per void volume) in n-pentane, flushing the column with two void volumes (5mL) of impregnation solution and heating the column for a short time to remove the solvent. The process takes about one hour, a significant time reduction compared to commonly used impregnation methods (17-23h)...
April 7, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28416215/stir-bar-sorptive-extraction-and-liquid-chromatography-tandem-mass-spectrometry-determination-of-polar-and-non-polar-emerging-and-priority-pollutants-in-environmental-waters
#18
Irene Aparicio, Julia Martín, Juan Luis Santos, José Luis Malvar, Esteban Alonso
An analytical method based on stir bar sorptive extraction (SBSE) was developed and validated for the determination of environmental concern pollutants in environmental waters by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Target compounds include six water and oil repellents (perfluorinated compounds), four preservatives (butylated hydroxytoluene and three parabens), two plasticizers (bisphenol A and di(2-ethylhexyl)phthalate), seven surfactants (four linear alkylbenzene sulfonates, nonylphenol and two nonylphenol ethoxylates), a flame retardant (hexabromocyclododecane), four hormones, fourteen pharmaceutical compounds, an UV-filter (2-ethylhexyl 4-methoxycinnamate) and nine pesticides...
April 7, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28420528/two-dimensional-gas-chromatography-with-electron-capture-detection-for-the-analysis-of-atmospheric-ozone-depleting-halocarbons
#19
Chang-Feng Ou-Yang, Hsi-Che Hua, Yu-Chieh Chou, Ming-Kai Teng, Wen-Tzu Liu, Jia-Lin Wang
This study is to develop a GC×GC method with electron capture detection (ECD) to analyze atmospheric halocarbons in the concentration range of parts per trillion by volume (pptv). To enrich atmospheric halocarbons a home-built thermal desorption (TD) device was coupled to the GC×GC-ECD. The technique of flow modulation was adopted using a Deans switch for GC×GC. Several column combinations of first and second dimensions were tested and the column set of DB-5×TG-1301 was found to show the best orthogonality for halocarbons...
April 4, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28416217/overcoming-speed-limits-in-high-throughput-chromatographic-analysis
#20
Kerstin Zawatzky, Chandan L Barhate, Erik L Regalado, Benjamin F Mann, Nicholas Marshall, Jeffrey C Moore, Christopher J Welch
The combination of high speed autosampler technology and ultrafast chromatographic separations enables faster high throughput analysis. With an injection cycle time of 10.6 s, MISER (Multiple Injection in a Single Experimental Run) HPLC-MS analysis of a 96 well microplate can be completed in only 17min. As chromatographic separations in the sub 5s range become increasingly common, even faster autosamplers will be needed to realize further speed improvements in high throughput LC-MS analysis. Indeed with proper hardware sampling approaches, chromatographic analysis of microplates could approach speeds of spectrophotometric plate readers while maintaining the advantage of multicomponent detection and monitoring...
April 4, 2017: Journal of Chromatography. A
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