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Journal of Chromatography. A

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https://www.readbyqxmd.com/read/28720223/absorbance-detector-for-high-performance-liquid-chromatography-based-on-a-deep-uv-light-emitting-diode-at-235nm
#1
João Flavio da Silveira Petruci, Michael G Liebetanz, Arnaldo Alves Cardoso, Peter C Hauser
In this communication, we describe a flow-through optical absorption detector for HPLC using for the first time a deep-UV light-emitting diode with an emission band at 235nm as light source. The detector is also comprised of a UV-sensitive photodiode positioned to enable measurement of radiation through a flow-through cuvette with round aperture of 1mm diameter and optical path length of 10mm, and a second one positioned as reference photodiode; a beam splitter and a power supply. The absorbance was measured and related to the analyte concentration by emulating the Lambert-Beer law with a log-ratio amplifier circuitry...
July 11, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28720218/pesticide-analysis-in-coffee-leaves-using-a-quick-easy-cheap-effective-rugged-and-safe-approach-and-liquid-chromatography-tandem-mass-spectrometry-optimization-of-the-clean-up-step
#2
Maria Teresa Salles Trevisan, Robert Wyn Owen, Pau Calatayud-Vernich, Andrea Breuer, Yolanda Picó
An analytical method using a quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure for multi-residue determination of 52 pesticides in coffee leaf extractshas been developed and validated according to SANTE/11945/2015 guidelines. Different sorbent combinations for dispersive solid phase extraction (d-SPE) clean-up as well as dispersive liquid-liquid microextraction (DLLME) were tested. The relative standard deviations (RSDs) for the recovery of 87-94% of pesticides added to coffee leaf extracts,was ≤20% for samples spiked at concentrations up to 50ng*g(-1) depending on the clean-up procedures...
July 11, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28712553/implications-of-phase-ratio-for-maximizing-peak-capacity-in-comprehensive-two-dimensional-gas-chromatography-time-of-flight-mass-spectrometry
#3
Brendon A Parsons, David K Pinkerton, Robert E Synovec
The relationship between the phase ratio, β, of the primary ((1)D) and secondary ((2)D) separation dimensions of comprehensive two-dimensional (2D) gas chromatography (GC×GC) separations, and the implications of β on realization of maximal 2D peak capacity, nc,2D, are examined. A GC×GC chromatographic system with time-of-flight mass spectrometry, TOFMS, was otherwise held constant for the separation of a multi-component test mixture spanning a range of chemical functionalities, while only the β of the two analytical columns were changed, (1)β for (1)D and (2)β for (2)D...
July 9, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28720224/development-of-a-1-0-mm-id-temperature-assisted-focusing-precolumn-for-use-with-2-1-mm-id-columns
#4
Stephen R Groskreutz, Anthony R Horner, Stephen G Weber
On-column solute focusing is a simple and powerful method to decrease the influence of precolumn band spreading and increase the allowable volume injected increasing sensitivity. It relies on creating conditions so that the retention factor, k', is transiently increased during the injection process. Both solvent composition and temperature control can be used to effect solute focusing. In the case of temperature, the release of the transiently delayed solute band requires increasing the temperature rapidly and with a minimum of radial thermal gradients...
July 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28720221/evaluation-of-nanoflow-liquid-chromatography-high-resolution-mass-spectrometry-for-pesticide-residue-analysis-in-food
#5
David Moreno-González, Patricia Pérez-Ortega, Bienvenida Gilbert-López, Antonio Molina-Díaz, Juan F García-Reyes, Amadeo R Fernández-Alba
This article reports on the evaluation of nanoflow liquid chromatography-mass spectrometry (LC-MS) for pesticide residue analysis in food. The approach is based on the use of reversed-phase C18nano columns with an integrated emitter, so that separation, ionization and detection are performed minimizing dead volumes. The use of nanoflow not only increases ionization efficiency and minimizes ionization suppression but also boost sensitivity compared to analytical-scale LC-MS methods. The nanoflow LC system was combined with full-scan high resolution mass spectrometry using a Q-Exactive Orbitrap instrument...
July 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28716356/fractionation-of-poly-methacrylic-acid-and-poly-vinyl-pyridine-in-aqueous-and-organic-mobile-phases-by-multidetector-thermal-field-flow-fractionation
#6
Guilaume Greyling, Harald Pasch
Multidetector thermal field-flow fractionation (ThFFF) is shown to be a versatile characterisation platform that can be used to characterise hydrophilic polymers in a variety of organic and aqueous solutions with various ionic strengths. It is demonstrated that ThFFF fractionates isotactic and syndiotactic poly(methacrylic acid) (PMAA) as well as poly(2-vinyl pyridine) (P2VP) and poly(4-vinyl pyridine) (P4VP) according to microstructure in organic solvents and that the ionic strength of the mobile phase has no influence on the retention behaviour of the polymers...
July 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28712554/improved-coverage-of-naphthenic-acid-fraction-compounds-by-comprehensive-two-dimensional-gas-chromatography-coupled-with-high-resolution-mass-spectrometry
#7
David T Bowman, Karl J Jobst, Xavier Ortiz, Eric J Reiner, Lesley A Warren, Brian E McCarry, Greg F Slater
This study reports the first application of comprehensive two-dimensional gas chromatography coupled to a high-resolution quadrupole time-of-flight mass spectrometer (GC×GC/HRQTOF-MS) for the characterization of naphthenic acid fraction compounds (NAFCs) from the Alberta Oil Sands. High resolution mass spectrometry (HRMS) significantly increased the coverage of NAFCs in the mixture and allowed the differentiation of NAFCs from several chemical classes. It was demonstrated that GC×GC, in combination with the high mass accuracy and precision of the HRQTOF-MS, could distinguish chemical species with the C3 vs SH4 mass split at a much lower resolving power than required with direct infusion experiments...
July 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28712551/facile-synthesis-of-thiol-polyethylene-glycol-functionalized-magnetic-titania-nanomaterials-for-highly-efficient-enrichment-of-n-linked-glycopeptides
#8
Jiawen Wang, Jizong Yao, Nianrong Sun, Chunhui Deng
As protein N-glycosylation involved in generation and development of various cancers and diseases, it is vital to capture glycopeptides from complex biological samples for biomarker discovery. In this work, by taking advantages of the interaction between titania and thiol groups, thiol-polyethylene glycol functionalized magnetic titania nanomaterials (denoted as Fe3O4@TiO2@PEG) were firstly fabricated as an excellent hydrophilic adsorbent of N-linked glycopeptides. On one hand, the special interaction of titanium-thiol makes the synthetic manipulation simple and provides a new idea for design and synthesis of novel nanomaterials; on the other hand, strong magnetic response could realize rapid separation and the outstanding hydrophilicity of polyethylene glycol makes Fe3O4@TiO2@PEG nanomaterials show superior performance for glycopeptides enrichment with ultralow limit of detection (0...
July 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28705585/a-four-dimensional-separation-method-based-on-continuous-heart-cutting-gas-chromatography-with-ion-mobility-and-high-resolution-mass-spectrometry
#9
Christian Lipok, Jörg Hippler, Oliver J Schmitz
A two-dimensional GC (2D-GC) method was developed and coupled to an ion mobility-high resolution mass spectrometer, which enables the separation of complex samples in four dimensions (2D-GC, ion mobilility spectrometry and mass spectrometry). This approach works as a continuous multiheart-cutting GC-system (GC+GC), using a long modulation time of 20s, which allows the complete transfer of most of the first dimension peaks to the second dimension column without fractionation, in comparison to comprehensive two-dimensional gas chromatography (GCxGC)...
July 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28693824/dispersive-solid-phase-microextraction-with-graphene-oxide-based-molecularly-imprinted-polymers-for-determining-bis-2-ethylhexyl-phthalate-in-environmental-water
#10
Lidong Cheng, Shuihong Pan, Chuyuan Ding, Jun He, Chengjun Wang
A novel graphene oxide-molecularly imprinted polymers (GO-MIPs) was prepared and applied for selective extraction and preconcentration of bis(2-ethylhexyl) phthalate (DEHP) in environmental water samples by using the dispersive solid-phase microextraction (DSPME) method. The GO-MIPs was synthesized via precipitation polymerization using GO, DEHP, methacrylic acid, and ethylene dimethacrylate as supporting materials, template molecules, functional monomer, and cross-linker, respectively. The prepared GO-MIPs were characterized by scanning electron microscope and Fourier transform infrared spectroscopy...
July 6, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28697933/a-simple-method-for-point-of-need-extraction-concentration-and-rapid-multi-mycotoxin-immunodetection-in-feeds-using-aqueous-two-phase-systems
#11
Ruben R G Soares, Ana M Azevedo, Pedro Fernandes, Virginia Chu, João P Conde, M Raquel Aires-Barros
The rapid detection of mycotoxins in feed samples is becoming an increasingly relevant challenge for the food production sector, in order to effectively enforce current regulations and assure food and feed safety. To achieve rapid mycotoxin detection, several biosensing strategies have been published, many reaching assay times of the order of a few minutes. However, the vast majority of these rely on sample preparation based on volatile organic solvents, often comprising complex multi-step procedures and devoid of clean-up and/or concentration effects...
July 5, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28697931/molecular-interaction-mechanisms-in-reverse-micellar-extraction-of-microbial-transglutaminase
#12
Tingting Yu, Mingxiang Lin, Junfen Wan, Xuejun Cao
Reverse micellar extraction is an efficient and economical alternative for protein purification. In this study, microbial transglutaminase (MTGase) from crude materials was purified using reverse micellar extraction, and the molecular interaction mechanism in reverse micellar extraction of MTGase was explored. By using a molecular simulation study, the interaction mechanism of forward extraction was investigated. The molecular simulation results reveal the interaction of MTGase-water-surfactant is the major driving force for the forward extraction...
July 5, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28689579/characterization-of-a-dicationic-imidazolium-based-ionic-liquid-as-a-gas-chromatography-stationary-phase
#13
Kourosh Tabar Heydar, Amir Mohammade Azadeh, Sadegh Yaghoubnejad, Nima Ghonouei, Ali Sharifi, Marzieh Afshin Rahnama
Here we report the characteristics of a new synthesized ionic liquid, 1,9-di(N-naphthalen-2-ylimidazolium)nonane bis[(trifluoromethyl)sulfonyl]imide ([C9(2NPTim)2][(NTf2)2]), as a stationary phase by inverse gas chromatography. The McReynolds constants demonstrated that the [C9(2NPTim)2][(NTf2)2] had an average polarity of 667 and polarity number P.N.=75, suggesting its polar nature. The solvation properties of the new stationary phase were determined by the calculation of Abraham solvation system constants, whereby the results showed that its major interactions with the analytes included H-bond basicity (a), dipole-dipole (s) and dispersive (l) interactions...
July 5, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28716355/study-of-relative-response-factors-and-mass-balance-in-forced-degradation-studies-with-liquid-chromatography-photo-diode-array-detector-evaporative-light-scattering-detector-mass-spectrometry-system
#14
Paula Hong, Aaron D Phoebe, Michael D Jones
A case study was performed using photodiode array detection (PDA) in combination with evaporative light scattering (ELS) detection and mass spectrometry (MS) to assess both mass balance and the relative response factors (RRFs) in the forced degradation studies of the drug substance, glimepiride. The RRF value, which is the ratio of the response factor of the impurity to that of the API, was first determined using calibration curves of standards. This conventional technique was compared to a second, multi-detection technique, which used the PDA and ELS detectors to determine both the ultraviolet (UV) peak area and the concentration (based on measurement by ELS) in a single analysis...
July 4, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28712549/determination-of-trace-amounts-of-g-type-nerve-agents-in-aqueous-samples-utilizing-in-vial-instantaneous-derivatization-and-liquid-chromatography-tandem-mass-spectrometry
#15
Avi Weissberg, Moran Madmon, Maor Elgarisi, Shai Dagan
A methodology for sensitive determination of sarin (GB), soman (GD) and cyclosarin (GF) chemical warfare agents in aqueous media was developed. The method incorporates direct derivatization with 2-[(dimethylamino)methyl]phenol (2-DMAMP), a commercially available, water-soluble reagent, followed by LC-ESI-MS/MS analysis in the positive ion mode. Five derivatization agents were characterized for their MS/MS fragmentation pattern, and their reaction time, temperature and derivatization-reagent amount were optimized...
July 4, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28705586/capillary-zone-electrophoresis-determination-of-aniline-and-pyridine-in-sewage-samples-using-transient-isotachophoresis-with-a-system-induced-terminator
#16
Takanari Hattori, Hideo Okamura, Satoshi Asaoka, Keiichi Fukushi
Transient isotachophoresis (tITP) with a system-induced terminator (SIT) was developed for capillary zone electrophoresis (CZE) determination of aniline (An(+)) and pyridine (Py(+)) in sewage samples. After sample injection, a water vial was set at the sample-inlet side. Then voltage was applied to generate a system-induced terminator (H(+)). Experiments and simulations revealed a concentration effect by tITP with an SIT: background electrolyte (BGE) - 100mM acetic acid (AcOH) and 50mM NaOH (pH 4.6); detection wavelength - 200nm for An(+) and 254nm for Py(+); vacuum injection period - 15s (190nL); SIT generation - 10kV applied for 80s with the sample inlet side anode; separation voltage - 20kV with the sample inlet side anode...
July 4, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28688721/separation-and-preparation-of-xanthochymol-and-guttiferone-e-by-high-performance-liquid-chromatography-and-high-speed-counter-current-chromatography-combined-with-silver-nitrate-coordination-reaction
#17
Jun Li, Ruixi Gao, Dan Zhao, Xianju Huang, Yu Chen, Fei Gan, Hui Liu, Guangzhong Yang
Xanthochymol (XCM) and guttiferone E (GFE), a pair of π bond benzophenone isomers from Garcinia xanthochymus, were once reported to be difficult or impossible to separate. The present study reports the successful separation of these two isomers through high performance liquid chromatography (HPLC), as well as their effective isolation using high speed counter-current chromatography (HSCCC) based on the silver nitrate (AgNO3) coordination reaction. First, an effective HPLC separation system was developed, achieving a successful baseline separation with resolution of 2...
July 4, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28720219/monitoring-leachables-from-single-use-bioreactor-bags-for-mammalian-cell-culture-by-dispersive-liquid-liquid-microextraction-followed-by-ultra-high-performance-liquid-chromatography-quadrupole-time-of-flight-mass-spectrometry
#18
N Dorival-García, J Bones
A method for the identification of leachables in chemically defined media for CHO cell culture using dispersive liquid-liquid microextraction (DLLME) and UHPLC-MS is described. A Box-Behnken design of experiments (DoE) approach was applied to obtain the optimum extraction conditions of the target analytes. Performance of DLLME as extraction technique was studied by comparison of two commercial chemically defined media for CHO cell culture. General extraction conditions for any group of leachables, regardless of their specific chemical functionalities can be applied and similar optimum conditions were obtained with the two media...
July 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28693825/sample-independent-approach-to-normalize-two-dimensional-data-for-orthogonality-evaluation-using-whole-separation-space-scaling
#19
Jaroslava Jáčová, Alžběta Gardlo, David Friedecký, Tomáš Adam, Jean-Marie D Dimandja
Orthogonality is a key parameter that is used to evaluate the separation power of chromatography-based two-dimensional systems. It is necessary to scale the separation data before the assessment of the orthogonality. Current scaling approaches are sample-dependent, and the extent of the retention space that is converted into a normalized retention space is set according to the retention times of the first and last analytes contained in a unique sample to elute. The presence or absence of a highly retained analyte in a sample can thus significantly influence the amount of information (in terms of the total amount of separation space) contained in the normalized retention space considered for the calculation of the orthogonality...
July 3, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28689578/a-systematic-investigation-of-sample-diluents-in-modern-supercritical-fluid-chromatography
#20
Vincent Desfontaine, Abhijit Tarafder, Jason Hill, Jacob Fairchild, Alexandre Grand-Guillaume Perrenoud, Jean-Luc Veuthey, Davy Guillarme
This paper focuses on the possibility to inject large volumes (up to 10μL) in ultra-high performance supercritical fluid chromatography (UHPSFC) under generic gradient conditions. Several injection and method parameters have been individually evaluated (i.e. analyte concentration, injection volume, initial percentage of co-solvent in the gradient, nature of the weak needle wash solvent, nature of the sample diluent, nature of the column and of the analyte). The most critical parameters were further investigated using in a multivariate approach...
July 3, 2017: Journal of Chromatography. A
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