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Resolution Mass Spectrometry (resolution + mass_spectrometry)
Selected AbstractsDIOS-MSEED: A chip-based method for measurement of enantiomeric excess by kinetic resolution/mass spectrometryISRAEL JOURNAL OF CHEMISTRY, Issue 4 2001Zhouxin Shen The determination of enantiomeric excess by kinetic resolution mass spectrometry has been implemented with the Desorption/Ionization On Silicon (DIOS) MS technique. Measurements can thereby be made much more rapidly than was previously possible, bringing this general methodology for screening asymmetric catalysts closer to true high-throughput status. [source] The role of mid-chain radicals in acrylate free radical polymerization: Branching and scissionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2008Thomas Junkers Abstract The past 5 years have seen a significant increase in the understanding of the fate of so-called mid-chain radicals (MCR), which are formed during the free radical polymerization of monomers that form highly reactive propagating radicals and contain an easily abstractable hydrogen atom. Among these monomers, acrylates are, beside ethylene, among the most prominent. Typically, a secondary propagating acrylate-type macroradical (SPR) can easily transfer its radical functionality via a six-membered transition state to a position within the polymer chain (in a so-called backbiting reaction), creating a tertiary MCR. Alternatively, the radical function can be transferred intramolecularly to any position within the chain (also forming an MCR) or intermolecularly to another polymer strand. This article aims at providing a comprehensive overview of the up-to-date knowledge about the rates at which MCRs are formed, their secondary reactions as well as the consequences of their occurrence under variable reaction conditions. We explore the latest aspects of their detection (via electron spin resonance spectroscopy) as well as the characterization of the polymer structures to which they lead (via high resolution mass spectrometry). The presence of MCRs leads to the formation of branched polymers and the partial formation of polymer networks. They also limit the measurement of kinetic parameters (such as the SPR propagation rate coefficient) with conventional methods. However, their occurrence can also be used as a synthetic handle, for example, the high-temperature preparation of macromonomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7585,7605, 2008 [source] Mass spectrometry analysis of the influenza virus,MASS SPECTROMETRY REVIEWS, Issue 1 2009Kevin M. Downard Abstract The role of mass spectrometry to probe characteristics of the influenza virus, and vaccine and antiviral drugs that target the virus, are reviewed. Genetic and proteomic approaches have been applied which incorporate high resolution mass spectrometry and mass mapping to genotype the virus and establish its evolution in terms of the primary structure of the surface protein antigens. A mass spectrometric immunoassay has been developed and applied to assess the structure and antigenicity of the virus in terms of the hemagglutinin antigen. The quantitation of the hemagglutinin antigen in vaccine preparations has also been conducted that is of importance to their efficacy. Finally, the characterization and quantitation of antiviral drugs against the virus, and their metabolites, have been monitored in blood, serum, and urine. The combined approaches demonstrate the strengths of modern mass spectrometric methods for the characterization of this killer virus. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 28:35,49, 2009 [This article was published online 10 September 2008. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected 7 November 2008.] [source] Observation of vanadyl porphyrins and sulfur-containing vanadyl porphyrins in a petroleum asphaltene by atmospheric pressure photonionization Fourier transform ion cyclotron resonance mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2008Kuangnan Qian Vanadyl (VO) porphyrins and sulfur-containing vanadyl (VOS) porphyrins of a wide carbon number range (C26 to C52) and Z-number range (,28 to ,54) were detected and identified in a petroleum asphaltene by atmospheric pressure photonionization (APPI) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). APPI provides soft ionization of asphaltene molecules (including VO and VOS porphyrins), generating primarily molecular ions (M+.). The ultra-high mass resolving power (m/,mFWHM ,500,K) of FTICR-MS enabled resolution and positive identification of elemental formulae for the entire family of VO and VOS porphyrins in a complicated asphaltene matrix. Deocophylerythro-etioporphyrin (DPEP) is found to be the most prevalent structure, followed by etioporphyrins (etio)- and rhodo (benzo)-DPEP. The characteristic Z-distribution of VO porphyrins suggests benzene and naphthene increment in the growth of porphyrin ring structures. Bimodal carbon number distributions of VO porphyrins suggest possible different origins of low and high molecular weight species. To our knowledge, the observation of VOS porphyrins in a petroleum product has not previously been reported. The work is also the first direct identification of the entire vanadyl porphyrin family by ultra-high resolution mass spectrometry without chromatographic separation or demetallation. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||