EarlyView Articles
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Bottom‐up proteome analysis of E . coli using capillary zone electrophoresis‐tandem mass spectrometry with an electrokinetic sheath‐flow electrospray interface
Published: Aug 1, 2013
Author(s): Xiaojing Yan, David C. Essaka, Liangliang Sun, Guijie Zhu, Norman J. Dovichi
Journal: PROTEOMICS
The Escherichia coli proteome was digested with trypsin and fractionated using SPE on a C18 SPE column. Seven fractions were collected and analyzed by CZE‐ESI‐MS/MS. The separation was performed in a 60‐cm‐long linear polyacrylamide‐coated capillary with a 0.1% v/v formic acid separation buffer. An electrokinetic sheath‐flow electrospray interface was used to couple the separation capillary with an Orbitrap‐Velos operating in...
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Comparison of nonaqueous hydrophilic interaction chromatography with aqueous normal‐phase chromatography on hydrosilated silica‐based stationary phases
Published: Jul 31, 2013
Author(s): Jan Soukup, Pavel Jandera
Journal: Journal of Separation Science
We investigated the retention behavior of phenolic acids in nonaqueous normal‐phase (NP) LC with buffered methanol/acetonitrile mobile phases on hydrosilated silica‐based stationary phases. The silica hydride, Diamond hydride, Bidentate C18, and Cholesterol columns showed a higher retention of phenolic acids in the nonaqueous mobile phases than in aqueous NP mobile phases. There are some selectivity differences between the aqueous and nonaqueous...
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The impact of column connection on band broadening in very high pressure liquid chromatography
Published: Jul 31, 2013
Author(s): Joseph J. Stankovich, Fabrice Gritti, Paul G. Stevenson, Georges Guiochon
Journal: Journal of Separation Science
A series of experiments was conducted to evaluate the degree of band broadening in very high pressure LC due to column connections. Different column manufacturers use slightly different designs for their column fittings. If the same column connections are repeatedly used to attach columns of different origins, different void volumes form between capillary tubes and column inlets. An Agilent Ultra Low Dispersion Kit (tubing id 75 μm) was...
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Analysis of pharmaceutical impurities using multi‐heartcutting 2D LC coupled with UV‐charged aerosol MS detection
Published: Jul 31, 2013
Author(s): Kelly Zhang, Yi Li, Midco Tsang, Nik P. Chetwyn
Journal: Journal of Separation Science
To overcome challenges in HPLC impurity analysis of pharmaceuticals, we developed an automated online multi‐heartcutting 2D HPLC system with hyphenated UV‐charged aerosol MS detection. The first dimension has a primary column and the second dimension has six orthogonal columns to enhance flexibility and selectivity. The two dimensions were interfaced by a pair of switching valves equipped with six trapping loops that allow...
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Multidimensional MR spectroscopic imaging of prostate cancer in vivo
Published: Jul 31, 2013
Author(s): M. Albert Thomas, Rajakumar Nagarajan, Amir Huda, Daniel Margolis, Manoj K. Sarma, Ke Sheng, Robert E. Reiter, Steven S. Raman
Journal: NMR in Biomedicine
Prostate cancer (PCa) is the second most common type of cancer among men in the United States. A major limitation in the management of PCa is an inability to distinguish, early on, cancers that will progress and become life threatening. One‐dimensional (1D) proton (1H) MRS of the prostate provides metabolic information such as levels of choline (Ch), creatine (Cr), citrate (Cit), and spermine (Spm) that can be used to detect and diagnose...
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In vivo investigation of cardiac metabolism in the rat using MRS of hyperpolarized [1‐ 13 C] and [2‐ 13 C]pyruvate
Published: Jul 31, 2013
Author(s): Sonal Josan, Jae Mo Park, Ralph Hurd, Yi‐Fen Yen, Adolf Pfefferbaum, Daniel Spielman, Dirk Mayer
Journal: NMR in Biomedicine
Hyperpolarized 13C MRS allows the in vivo assessment of pyruvate dehydrogenase complex (PDC) flux, which converts pyruvate to acetyl‐coenzyme A (acetyl‐CoA). [1‐13C]pyruvate has been used to measure changes in cardiac PDC flux, with demonstrated increase in 13C‐bicarbonate production after dichloroacetate (DCA) administration. With [1‐13C]pyruvate, the 13C label is released as 13CO2/13C‐bicarbonate, and, hence, does not allow us to follow the fate of acetyl‐CoA. Pyruvate...
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Near‐field optical enhancement by lead‐sulfide quantum dots and metallic nanoparticles for SERS
Published: Jul 30, 2013
Author(s): Tanya Hutter, Sumeet Mahajan, Stephen R. Elliott
Journal: Journal of Raman Spectroscopy
There is a growing interest in using quantum dots (QDs) and metallic nanoparticles (NPs), both for luminescence enhancement and surface‐enhanced Raman scattering (SERS). Here, we study the electromagnetic‐field enhancement that can be generated by lead‐sulfide (PbS) QDs using three‐dimensional finite‐element simulations. We investigate the field enhancement associated with combinations of PbS QDs with metallic NPs and substrates. The...
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Coherent optical phonons in alexandrite crystal studied by Optical Kerr Effect spectroscopy
Published: Jul 30, 2013
Author(s): K. Polok, J. Konarska, B. Ratajska‐Gadomska, W. Gadomski
Journal: Journal of Raman Spectroscopy
Herewith, we report on the first observation of coherent phonons in alexandrite crystal obtained by means of the femtosecond Optical Kerr Effect spectroscopy. We have managed to observe dynamics of the Raman‐active modes with high resolution and to find their lifetimes in the temperature range between 263 K and 373 K. We have used the obtained temperature dependence of phonon lifetimes and frequencies for calculation of the anharmonic...
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Raman comparison of skin dermis of different ages: focus on spectral markers of collagen hydration
Published: Jul 30, 2013
Author(s): The Thuong Nguyen, Teddy Happillon, Jezabel Feru, Sylvie Brassart‐Passco, Jean‐François Angiboust, Michel Manfait, Olivier Piot
Journal: Journal of Raman Spectroscopy
Skin aging is the most visible sign of aging of the body. This complex process involves molecular and structural alterations of the main skin constituents. The major cutaneous constituent is type I collagen that gives strength and resilience to the skin. This macromolecule possesses a particular triple helix structure and is arranged in the form of a fibrous network. Water plays a crucial role for maintaining this molecular assembly which...
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Discrimination of cathinone regioisomers, sold as ‘legal highs’, by Raman spectroscopy
Published: Jul 30, 2013
Author(s): R. Christie, E. Horan, J. Fox, C. O'Donnell, H. J. Byrne, S. McDermott, J. Power, P. Kavanagh
Journal: Drug Testing and Analysis
The discrimination of a cross section of cathinone regioisomers, sold as ‘legal highs’, using Raman spectroscopy, is reported here. Mephedrone and flephedrone were identified in ‘legal high’ products sold in Irish head shops, and their 2, 3 and 4‐isomers were synthesized as reference standards. The 3,4‐methylenedioxy substituted cathinones, methylone, butylone and methylenedioxypyrovalerone (MDPV), were also identified in ‘legal highs’...
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Restricted access media as a streamlined approach toward on‐line sample preparation: Recent advancements and applications
Published: Jul 30, 2013
Author(s): Samuel H. Yang, Hui Fan, Robert J. Classon, Kevin A. Schug
Journal: Journal of Separation Science
Restricted access media (RAM) as an alternative to traditional sample preparation strategies are reviewed. RAM comprise chromatographic packing materials that combine, typically, a restrictive outer surface to exclude the retention of large biomolecules, which are common interferences in biological fluids, with retentive inner pores or phases to capture analytes of interest. Through the years, a variety of RAM formats have been created,...
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Poly(ethylene glycol)‐based monolithic capillary columns for hydrophobic interaction chromatography of immunoglobulin G subclasses and variants
Published: Jul 30, 2013
Author(s): Christopher T. Desire, R. Dario Arrua, Mohammad Talebi, Nathan A. Lacher, Emily F. Hilder
Journal: Journal of Separation Science
Polymer monoliths were prepared in 150 μm id capillaries by thermally initiated polymerization of PEG diacrylate for rapid hydrophobic interaction chromatography of immunoglobulin G (IgG) subclasses and related variants. Using only one monomer in the polymerization mixture allowed ease of optimization and synthesis of the monolith. The performance of the monolith was demonstrated by baseline resolution of IgG subclasses and variants,...
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Characterization of a high field O rbitrap mass spectrometer for proteome analysis
Published: Jul 30, 2013
Author(s): Fiona Pachl, Benjamin Ruprecht, Simone Lemeer, Bernhard Kuster
Journal: PROTEOMICS
The field of proteomics continues to be driven by improvements in analytical technology, notably in peptide separation, quantitative MS, and informatics. In this study, we have characterized a hybrid linear ion trap high field Orbitrap mass spectrometer (Orbitrap Elite) for proteomic applications. The very high resolution available on this instrument allows 95% of all peptide masses to be measured with sub‐ppm accuracy that in turn...
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Ultrahigh pressure fast size exclusion chromatography for top‐down proteomics
Published: Jul 30, 2013
Author(s): Xin Chen, Ying Ge
Journal: PROTEOMICS
Top‐down MS‐based proteomics has gained a solid growth over the past few years but still faces significant challenges in the LC separation of intact proteins. In top‐down proteomics, it is essential to separate the high mass proteins from the low mass species due to the exponential decay in S/N as a function of increasing molecular mass. SEC is a favored LC method for size‐based separation of proteins but suffers from notoriously low...
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Proteome analysis reveals antiangiogenic environments in chronic wounds of diabetes mellitus type 2 patients
Published: Jul 30, 2013
Author(s): Christoph Krisp, Frank Jacobsen, Matthew J. McKay, Mark P. Molloy, Lars Steinstraesser, Dirk A. Wolters
Journal: PROTEOMICS
In contrast to normal healing wounds, chronic wounds commonly show disturbances in proteins regulating wound healing processes, particularly those involved in cell proliferation and protein degradation. Multidimensional protein identification technology MS/MS was conducted to investigate and compare the protein composition of chronic diabetic foot exudates to exudates from split‐skin donor sites of burn victims otherwise healthy. Spectral...
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Oncogene‐induced cellular senescence elicits an anti‐ W arburg effect
Published: Jul 30, 2013
Author(s): Mingxi Li, Kenneth R. Durbin, Steve M. M. Sweet, Jeremiah D. Tipton, Yupeng Zheng, Neil L. Kelleher
Journal: PROTEOMICS
Cellular senescence, an irreversible cell cycle arrest induced by a diversity of stimuli, has been considered as an innate tumor suppressing mechanism with implications and applications in cancer therapy. Using a targeted proteomics approach, we show that fibroblasts induced into senescence by expression of oncogenic Ras exhibit a decrease of global acetylation on all core histones, consistent with formation of senescence‐associated heterochromatic ...
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Critical assessment of proteome‐wide label‐free absolute abundance estimation strategies
Published: Jul 30, 2013
Author(s): Erik Ahrné, Lars Molzahn, Timo Glatter, Alexander Schmidt
Journal: PROTEOMICS
There is a great interest in reliable ways to obtain absolute protein abundances at a proteome‐wide scale. To this end, label‐free LC‐MS/MS quantification methods have been proposed where all identified proteins are assigned an estimated abundance. Several variants of this quantification approach have been presented, based on either the number of spectral counts per protein or MS1 peak intensities. Equipped with several datasets...
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Liquid chromatography–tandem mass spectrometry of porphyrins and porphyrinogens in biological materials: separation and identification of interfering poly(ethylene) glycol by travelling wave ion mobility spectrometry/tandem mass spectrometry
Published: Jul 29, 2013
Author(s): Christopher M. Benton, Chang Kee Lim, Caje Moniz, Donald J. L. Jones
Journal: Biomedical Chromatography
ABSTRACT Biological and clinical samples for porphyrin and porphyrinogen analyses by liquid chromatography–tandem mass spectrometry (LC‐MS/MS) are often contaminated with poly(ethylene)glycol (PEG), which complicates the interpretation of mass spectra and characterisation of new porphyrin metabolites. Two contaminating PEG molecules (m/z 833 and m/z 835) were completely separated from uroporphyrin I (m/z 831) by travelling wave ion mobility...
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Effects of elevated levels of lead in ceramics on provenancing studies using non‐destructive PXRF: a case study in Byzantine Cypriot glazed ceramics
Published: Jul 29, 2013
Author(s): Nicola Forster, Peter Grave
Journal: X-Ray Spectrometry
Glazed ceramics are ubiquitous in the medieval archaeological record in the Mediterranean. The effects of lead volatilisation during firing of glazed ceramics on non‐destructive PXRF (portable X‐ray fluorescence) are evaluated using 25 Byzantine Cypriot glazed ceramics. Significant spectral interferences reduce the number of discriminating elements for multivariate statistical analysis, limiting the capacity of non‐destructive PXRF to...
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Development of a new in‐vial standard gas system for calibrating solid‐phase microextraction in high‐throughput and on‐site applications
Published: Jul 29, 2013
Author(s): German A. Gómez‐Ríos, Nathaly Reyes‐Garcés, Janusz Pawliszyn
Journal: Journal of Separation Science
In this work, an innovative, reproducible, and reusable standard generator vial is presented. The standard generator vial consists of vacuum‐pump oil doped with McReynolds probes (benzene, 2‐pentanone, pyridine, nitropropane, 1‐pentanol, and n‐octane) mixed with a polystyrene‐divinylbenzene resin without functional groups. The evaluation of this vial was fully automated on a multifiber exchanger system and the extraction/desorption cycle, together...
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