排序方式: 共有47条查询结果,搜索用时 500 毫秒
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Christopher M. Benton Chang Kee Lim Caje Moniz Donald J. L. Jones 《Biomedical chromatography : BMC》2013,27(12):1782-1787
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 spectrometry and characterised by tandem mass spectrometry. One of the PEG species (m/z 835) also co‐eluted with uroporphyrinogen I (m/z 837) and was unresolvable by travelling wave ion mobility spectrometry/MS, therefore contaminating the MS/MS mass spectra owing to isotope distribution. These PEG species, with the [M + H]+ ions at m/z at 833 and/or m/z 835, co‐eluted with uroporphyrin I and uroporphyrinogen I by LC‐MS/MS and could be wrongly identified as uroporphomethenes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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The anion radicals of a number of siloxanes bearing phenyl and methyl substituents have been prepared by metal reduction. The cleavage and reaction mechanisms of these radica s have been studied by ESR, and interpretations have been made regarding the structures of the radicals. 相似文献
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Vallejos S Stoycheva T Umek P Navio C Snyders R Bittencourt C Llobet E Blackman C Moniz S Correig X 《Chemical communications (Cambridge, England)》2011,47(1):565-567
A new method of synthesising nanoparticle-functionalised nanostructured materials via Aerosol Assisted Chemical Vapour Deposition (AACVD) has been developed. Co-deposition of Au nanoparticles with WO(3) nanoneedles has been used to deposit a sensing layer directly onto gas sensor substrates providing devices with a six-fold increase in response to low concentrations of a test analyte (ethanol). 相似文献
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Benton CM Lim CK Moniz C Jones DJ 《Rapid communications in mass spectrometry : RCM》2011,25(24):3749-3757
An ultra-high-performance liquid chromatography/electrospray ionisation tandem mass spectrometry system is described for the separation and characterisation of uroporphyrinogen, heptacarboxylic acid porphyrinogen, hexacarboxylic acid porphyrinogen, pentacarboxylic acid porphyrinogen and coproporphyrinogen. The separation was carried out on a 100 mm × 2.1 mm Thermo-Hypersil BDS column (2.4 μm average particle size) by gradient elution with a mixture of acetonitrile, methanol and 1 mol/L aqueous ammonium acetate buffer, pH 5.16, as eluent. The fragmentation pattern of each compound was established by collision-induced dissociation tandem mass spectrometry. The most characteristic fragmentation was ring opening at one of the four methylene bridges of the protonated porphyrinogen molecule followed by further cleavages of methylene bridges linking the four pyrrole rings at various points to give product ions with methylenepyrrolenine, methylene-dipyrrolenine and methylene-tripyrrolenine structures. 相似文献