Journal of the Mass Spectrometry Society of Japan
Online ISSN : 1880-4225
Print ISSN : 1340-8097
ISSN-L : 1340-8097
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Volume 44, Issue 6
Displaying 1-4 of 4 articles from this issue
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REVIEW
INTEGRATED PAPERS
  • Collisional Activation by the Fast Particle
    Kenzo HIRAOKA
    1996 Volume 44 Issue 6 Pages 577-624
    Published: 1996
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.44.577
    JOURNAL FREE ACCESS
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    Collisional activation of the matter induced by the bombardment of the fast particle is summarized. The particle with the velocity higher than the Bohr velocity (transit time through 5A shorter than 2.5×10-16s) experiences the electronic stopping power when it passes through the matter and induces dense electronic excitations and ionizations which results in the heavy sputtering of the matter. This kind of activation is usefully applied in the PDMS. When the particle velocity becomes lower than the Bohr velocity, the energy is mainly deposited to the matter by the nuclear stopping power, i.e., energy loss is governed by the screened Coulombic collisions of the atoms giving rise to the momentum transfer to the target nuclei. When the transit time of the particle through 5A is between 2.5×10-16-10-14 s, the electronic excitation and ionization take place by the collision. These phenomena are fully utilized in the FAB/SIMS and CID techniques. With the transit time in the range of 10-14-2.5×10-13s, the velocity is not high enough for the electronic excitation and the particle loses its energy mainly by the vibrational and phonon excitation of the target. This range of the velocity corresponds to that of the massive cluster impact ionization. With the velocity equal to or lower than 2.5×10-13s, the energy of the incident particle is consumed mainly by the phonon excitation and the collision results in the modest heating of the colliding interface between the projectile and the target. This range of the velocity is successfully used in the ionized cluster beam technique developed by Takagi of the Kyoto University.
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  • Determination of Organic Constituents in Human Serum by Isotope Dilution Method Using Discharge-assisted Thermospray Liquid Chromatography Mass Spectrometry
    Akiko TAKATSU
    1996 Volume 44 Issue 6 Pages 625-639
    Published: 1996
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.44.625
    JOURNAL FREE ACCESS
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    We review recently developed isotope dilution methods using discharge-assisted thermospray (plasmaspray) liquid chromatography/mass spectrometry (LC/MS) for determination of total cholesterol, glucose, creatinine, and urea in human serum. We have optimized the analytical conditions and discussed the analytical performances of the LC/MS methods. With an optimal conditions, the relative standard deviation of LC/MS methods was between 0.5 and 1.3%. We could conclude that the LC/MS method has the advantage in its simplicity of sample preparation, compared with the GC/MS, and could be a useful technique in IDMS analysis.
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REGULAR PAPER
  • Molecular Mass Measurement of Hydrophobic and Aggregative Virus Proteins to Confirm Sequence Variation and Post-translational Modification by Electrospray Ionization and Array Detection
    Keiichiro ISHIKAWA, Toshihiro OMURA, Yoshinori KOGA, Yoshio NIWA, Masa ...
    1996 Volume 44 Issue 6 Pages 641-652
    Published: 1996
    Released on J-STAGE: July 20, 2007
    DOIhttps://doi.org/10.5702/massspec.44.641
    JOURNAL FREE ACCESS
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    Molecular mass measurements have been studied of outer capsid proteins (P8, -46 kDa) of rice dwarf virus (RDV) by electrospray ionization (ESI) and array detection on a high performance magnetic sector instrument. P8 proteins were highly hydrophobic and aggregative and, therefore, hardly soluble in ESI solvents. Use of an array detector was essential to compensate for the extremely low concentration of solubilized P8 proteins. Extensive tailing of the peak profiles of multiply charged proteins made it difficult to determine their center of gravity representing relative molecular masses (Mr). In stead of Mr, top positions of unresolved peak profiles were utilized which gave molecular masses of the most abundant isotope ions (Ma) at a precision of 0.002%. Precise Ma of P8 proteins suggested the presence of an yet unknown post-translational modification, which was identified as N-terminal acetylation by the sequence analysis of V8-protease digests by FAB-MS/MS. Further, a small difference in Ma (12.3±2.1 Da) between P8 proteins from the ordinary (RDV-O) and the severe (RDV-S) strains of RDV allowed the confirmation of the strain specific amino acid substitution predicted by nucleotide sequencing. The applicability of ESI-MS in combination with array detection was demonstrated for less soluble proteins of biological importance.
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