|
| ||
|
|
||
Chromatography/electrospray Ionisation Mass Spectrometry (chromatography + ionisation_mass_spectrometry)
Kinds of Chromatography/electrospray Ionisation Mass Spectrometry Selected AbstractsA kinetic study of the reactions of (+)-catechin with aldehydes derived from toasted oakJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2007Marie-Françoise Nonier Abstract The reactions between (+)-catechin and representative oak wood furanic (furfuraldehyde, 5-hydroxymethylfurfuraldehyde and 5-methylfurfuraldehyde) and phenolic (vanillin and syringaldehyde) aldehydes in a wine-like model solution were studied and the corresponding condensation kinetics at pH 3.0 and 3.5 were compared. A comparative study on the reactivity of these two representative families of aldehydes towards (+)-catechin showed a large difference between them. When incubated separately with (+)-catechin at both pH values, the reactions were faster with furanic aldehydes than with phenolic aldehydes. In mixtures containing (+)-catechin and individual aldehydes, new compounds were identified by high-performance liquid chromatography (HPLC)/UV,visible detection, some of which were characterised by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS). The increase in solution absorbance with time was closely linked to these new products. Copyright © 2007 Society of Chemical Industry [source] Characterisation of oxazepam degradation products by high-performance liquid chromatography/electrospray ionisation mass spectrometry and electrospray ionisation quadrupole time-of-flight tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2010Thomas J. P. Smyth Oxazepam has been subjected to controlled degradation at 100°C for 3,h in 0.5,M HCl and 0.5,M NaOH. Following neutralisation of the degradation mixture and removal of salts by solid-phase extraction (SPE), isocratic high-performance liquid chromatography/mass spectrometry (HPLC/MS) using water/methanol (25:75,v/v) as the mobile phase was carried out using a flow diverter to collect fractions prior to their characterisation by electrospray ionisation multi-stage mass spectrometry (ESI-MSn) and proposal of the corresponding fragmentation patterns. The elemental compositions of the degradation products and their MS fragments were evaluated using electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) which was then used to support the proposed fragmentation patterns. Copyright © 2010 John Wiley & Sons, Ltd. [source] Identification of an unusual naturally occurring apolar fatty acid amide in mammalian brain and a method for its quantitative determinationRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2006Maurizio Dalle Carbonare Fatty acid amides (FAAs), such as the N -acylamides, N -acylethanolamides, N -acyldopamines and N -acylamino acids, are now emerging as an important new class of lipid-signalling molecules. This paper provides evidence, based on high-performance liquid chromatography/electrospray ionisation mass spectrometry (HPLC/ESI-MS/MS), gas chromatography/mass spectrometry (GC/MS) and 1H-NMR, of the occurrence in mouse and bovine brain extracts of a compound characterised by a mass spectrum attributable to a FAA not previously described, namely, the isopropyl-amide of stearic acid (SIPA). A highly sensitive GC/MS method was developed for quantification of naturally occurring SIPA and, also, for purposes of comparison, that of palmitoylethanolamide (PEA), a structurally related compound commonly determined in animal tissues. The results obtained show that SIPA levels in mouse brain are 8,10-fold higher than those of PEA. Moreover, SIPA was found in human neuroblastoma cell (SHSY-5Y) extracts, at significantly higher levels following exposure of the cells to the mitochondrial inhibitor rotenone. All this evidence not only shows surprisingly that SIPA may be found naturally in mammalian biological extracts despite the unusual functional group (i.e. isopropylamide) implicated, but also raises many important questions concerning its biological origin. Copyright © 2005 John Wiley & Sons, Ltd. [source] Detection of phenolic oxidation products in cider apple juice by high-performance liquid chromatography electrospray ionisation ion trap mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2004S. Bernillon Juice was prepared from cider apples of the cultivar "Kermerrien" under oxidative conditions. After isolation by solid-phase extraction, the phenolic fraction was subjected to high-performance liquid chromatography/electrospray ionisation mass spectrometry. SIM scans were performed at m/z values obtained in model solutions. The oxidation products, resulting from coupling between a molecule of caffeoylquinic acid and caffeoylquinic acid, catechin or dimeric flavan-3-ol, were detected. Copyright © 2004 John Wiley & Sons, Ltd. [source] Derivatisation for liquid chromatography/electrospray mass spectrometry: synthesis of pyridinium compounds and their amine and carboxylic acid derivativesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2003Samantha J. Barry A simple method has been developed for the pre-column derivatisation of low molecular weight primary and secondary amines and carboxylic acids using quaternary nitrogen compounds to enhance their detection by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS). The synthesis of seven novel quaternary nitrogen reagents is described. The derivatives are designed to be relatively small molecules to avoid some of the steric hindrance problems that may be associated with larger derivatisation reagents. The compounds have amine and carboxylic acid functional groups with which to derivatise carboxylic acids and amines, respectively. Two of the compounds contain a bromine atom in order to assess the advantages of a bromine isotope pattern in the mass spectra. This acts as a simple marker for derivatisation and enables data processing by cluster analysis. Activation of the carboxylic acid group was achieved by the use of either 1-chloro-4-methylpyridinium iodide (CMPI) or the more reactive 1-fluoro-4-methylpyridinium p -toluenesulphonate (FMP).1 Using both of these active reagents, the degree of nucleophilic substitution was investigated for the derivatisation of a variety of small molecules. Whilst giving some increase in the ESI-MS response for the derivatised compounds, the FMP itself acted as a derivatising reagent in a competing reaction. In the light of this finding, FMP was reacted with the test compounds separately and gave positive results as a derivatising reagent. Detection of the ,pre-charged' derivatives of amines and carboxylic acids by LC/ESI-MS was investigated with respect to their ESI response and chromatography. Copyright © 2003 John Wiley & Sons, Ltd. [source] A novel approach for identification and measurement of hemoglobin adducts with 1,2,3,4-diepoxybutane by liquid chromatography/electrospray ionisation mass spectrometry and matrix-assisted laser desorption/ionisation tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2001Adriana Basile The structural characterisation of the adducts formed by in vitro interaction of hemoglobin (Hb) with 1,2,3,4-diepoxybutane (DEB), the most reactive 1,3-butadiene (BD) metabolite, was obtained by liquid chromatography/electrospray ionisation mass spectrometry (LC/ES-MS) analysis of modified tryptic peptides of human hemoglobin chains. The reactive sites of human hemoglobin towards DEB and its hydroxylated derivatives (trihydroxybutyl (THB)-derivatives) were identified through the characterisation of alkylated tryptic peptides by matrix-assisted laser desorption/ionisation tandem mass spectrometry (MALDI-MS/MS). Based on this characterisation, a procedure was set up to measure the Hb-adducts of THB-derivatives by isotope dilution mass spectrometry with the use of a deuterated peptide standard. The results obtained here could permit optimisation of molecular dosimetry of BD-adducts, and extension of the analysis to the biological monitoring of occupational exposure to butadiene. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||