Journal of the Mass Spectrometry Society of Japan
Online ISSN : 1880-4225
Print ISSN : 1340-8097
ISSN-L : 1340-8097
Volume 53, Issue 6
Displaying 1-5 of 5 articles from this issue
REGULAR PAPERS
  • Yoko KAWAI, Yoshiki OKADA, Satoru YAMAGUCHI, Kazuo TAKEUCHI, Yusuke YA ...
    2005 Volume 53 Issue 6 Pages 305-308
    Published: 2005
    Released on J-STAGE: April 05, 2006
    JOURNAL FREE ACCESS
    We investigated isotope effects in the reactions of protonated water dimer ions H+(H2O)2/D+(D2O)2 with acetone and dimethylsulfoxide (DMSO) using a guided ion beam apparatus. The reaction cross section, σr, of H+(H2O)2 with acetone was found to be slightly larger than that of D+(D2O)2 at low collision energies, <0.5 eV, where the ratio of the σr, was less than 1.5. The σr of H+(H2O)2 with DMSO was approximately twice as large as that of D+(D2O)2 with DMSO. Major reaction products were Y+X, where Y=H, D and X=acetone, DMSO. We examine two possible reaction processes, the proton transfer reaction via intermediate compounds and direct proton transfer.
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  • Yoko OHASHI, Hiroshi HATASE, Mitsuhiro NAKAMURA, Takashi HIRANO, Shoji ...
    2005 Volume 53 Issue 6 Pages 309-314
    Published: 2005
    Released on J-STAGE: April 05, 2006
    JOURNAL FREE ACCESS
    ESIMS/MS was employed for the analyses of 1-13CO-labeled amino acids. Conventionally, in order to estimate the 13C-content, the intensity of molecule-related ion of the sample has been compared against the natural compound. However, this method is incompetent for specifying the position of the 13C-labeling, hence is unable to distinguish the specifically 1-13C-labeled compound from otherwise-(generally or non-specifically) labeled amino acids. With the intention of distinguishing 1-13CO-labeled amino acids from generally labeled and non-labeled molecules we utilized ESIMS/MS in the selected reaction monitoring mode, choosing the protonated molecules as the precursor ion and specifying the product ion generated by a 47 u- (instead of 46 u-) elimination from the precursor ion for the labeled samples. By this new method, characterization of solely 1-13CO-labeled amino acids has been successfully conducted, enabling their distinction from otherwise-labeled compounds.
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NOTE
  • Noritaka MOCHIZUKI, Akira WADA, Hiroshi OKADA, Toshiyasu ICHIKAWA, Isa ...
    2005 Volume 53 Issue 6 Pages 315-317
    Published: 2005
    Released on J-STAGE: April 05, 2006
    JOURNAL FREE ACCESS
    Gas-phase ion/molecule reactions in tetrafluoroethylene (C2F4) were studied with a pulsed electron beam mass spectrometer. When a few Torr of major gas, N2, containing 1-10 mTorr C2F4 was ionized by 2 keV electrons, CF3+ and C2F4+ were formed as major ions. CF3+ reacted with C2F4 rapidly to form C3F7+. The rate constant of reaction C2F4++C2F4→C3F5++CF3 was measured to be (1.5±0.5)×10-11 cm3/molecule·s and found to be temperature-independent in the range of 180-310 K.
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INTEGRATED PAPER
  • Yutaka TAKAHASHI
    2005 Volume 53 Issue 6 Pages 319-328
    Published: 2005
    Released on J-STAGE: April 05, 2006
    JOURNAL FREE ACCESS
    A new technique is described for accurate mass measurement by using multiple sprayers nano electrospray ionization mass spectrometry (nano-ESI/MS). A nano-scale high-performance liquid chromatography (nano-LC) was combined with a magnetic sector instrument. A metal-coated glass capillary was used for the introduction of the reference compound solution, and a metal-coated fused silica capillary was used to connect the nano-LC column to ionization chamber. By shifting the position of the each sprayers to the sampling orifice, the spectra were obtained for the sample compounds eluted from the column and the reference one. Several standard compounds were examined by using this technique and satisfactory accurate masses were obtained. It was not problems for the differences between the ionization efficiency of the sample and the reference compounds. Studies on the unimolecular metastable ion decomposition of several organic compounds are also described by using high-resolution mass spectrometry, MIKE (mass-analyzed ion kinetic energy) spectrometry and D-labeling technique. The m/z 45 ions generated from 2-methoxyethylamine (CH3OCH2CH2NH2) consist of two isobaric ions, methoxymethyl ion, CH3OCH2+, and C2H7N+. The m/z 69 ions generated from methyl trifluoroacetoacetate (CF3COCH2COOCH3) and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (CF3COCH2COCF3) also consist of two isobaric ions, trifluoromethyl ion, CF3+, and protonated carbon suboxide, OCCH+CO.
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TECHNICAL REPORT
  • Shinichi YAMAGUCHI
    2005 Volume 53 Issue 6 Pages 329-333
    Published: 2005
    Released on J-STAGE: April 05, 2006
    JOURNAL FREE ACCESS
    Although various multi-turn geometries of time-of-flight mass spectrometry (TOF MS) have been devised recently, they still suffer from a practical problem in analysis for a wide mass range. The relationship between flight time and mass to charge ratio (m/z) is not as simple as the conventional TOF MS. Because the flight length may change with m/z, turn numbers of ions must be figured out for each peak in a multi-turn TOF spectrum. This article describes a method to determine turn numbers of ions in multi-turn TOF MS. The key idea is a combination of multi-turn and reflector TOF geometries. Because a change in the reflector conditions can introduce m/z-dependent perturbation into the flight times, it is possible to estimate approximate m/z values from degrees of the perturbation. This rough estimation helps to determine the numbers of turns corresponding to m/z values. Finally the precise m/z values are derived from the numbers of turns and flight times.
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