Journal of the Mass Spectrometry Society of Japan
Online ISSN : 1880-4225
Print ISSN : 1340-8097
ISSN-L : 1340-8097
Volume 51, Issue 2
Displaying 1-6 of 6 articles from this issue
REGULAR PAPERS
  • Daisuke OKUMURA, Michisato TOYODA, Morio ISHIHARA, Itsuo KATAKUSE
    2003 Volume 51 Issue 2 Pages 349-353
    Published: 2003
    Released on J-STAGE: October 16, 2007
    JOURNAL FREE ACCESS
    A new multi-turn time-of-flight mass spectrometer ‘MULTUM II’ was constructed. The ion optical system was simplified comparing with ‘MULTUM Linear plus’. The multi-turn part of the new instruments consisted of only four toroidal electric sector fields. The mean radius of cylindrical electric sector was 50 mm and the deflection angle was 157.1°. The total flight pass length of one cycle was 1.308 m. In a preliminary experiment, the mass spectra of Xe ion were measured and enhancement in mass resolution with increasing number of cycles was obserbed. The mass resolution 5100 at m/z 136 was achieved after 10 cycles.
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  • Takaya SATOH, Hiroyuki ITO, Hiroki SAKAE, Toshio ICHIHARA, Itsuo KATAK ...
    2003 Volume 51 Issue 2 Pages 354-358
    Published: 2003
    Released on J-STAGE: October 16, 2007
    JOURNAL FREE ACCESS
    The lifetime distribution of silver and mercury-silver binary cluster ions from a sputtering ion source was investigated. The cluster ions were produced by 10 keV Xe ion bombardment on a mercury-silver amalgam for mercury-silver binary clusters, and a silver plate for silver clusters. The fragmentation rates were obtained from experimental data at several positions of the mass spectrometer. The lifetime distribution was calculated using fragmentation rates. The distribution was found to be rather power functional than exponential, because of the wide distribution of lifetimes for cluster ions. The cluster ion, Hg12Ag+, which might have an icosahedron structure turned out to be more stable than neighboring clusters.
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  • Yutaka TAKAHASHI, Fukiko HASEGAWA, Chinatsu TANAKA, Yuko HIROI, Susumu ...
    2003 Volume 51 Issue 2 Pages 359-364
    Published: 2003
    Released on J-STAGE: October 16, 2007
    JOURNAL FREE ACCESS
    The characterization and metastable decomposition of isobaric ions from several compounds are described by using high-resolution mass spectrometry (HR-MS) and mass-analyzed ion kinetic energy (MIKE) spectrometry. The m/z 45 ions from 2-methoxyethylamine, CH3OCH2CH2NH2 (1) consists of two isobaric ions, methoxymethyl ion, CH3OCH2+, and C2H7N+ ion. The former decomposes into the m/z 29 ion by losing CH4 in metastable time window. Although the latter decomposes into the m/z 30 and 18 ions, its structure could not be confirmed in this study. The m/z 69 ions generated from methyl trifluoroacetoacetate, CF3COCH2COOCH3 (2) and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, CF3COCH2COCF3 (3) also consists of two isobaric ions, trifluoromethyl ion, CF3+, and protonated carbon suboxide, OCCHCO+. The former does not decompose into any ions in the metastable time window. On the other hand, the latter decomposes into m/z 41 ion by losing CO.
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NOTE
  • Susumu TAJIMA, Daisuke WATANABE, Satoshi NAKAJIMA, Nico M. M. NIBBERIN ...
    2003 Volume 51 Issue 2 Pages 365-367
    Published: 2003
    Released on J-STAGE: October 16, 2007
    JOURNAL FREE ACCESS
    Unimolecular metastable ion decompositions of acetyltrimethyl silane, CH3COSi(CH3)3 (MW: 116, (1)) generated by electron ionization, have been investigated by use of mass-analyzed ion kinetic energy (MIKE) spectrometry and D-labeling. In the metastable time window, the molecular ions 1+ • decompose exclusively into the ions at m/z 101, [M-CH3]+. A considerable extent of H/D exchange occurs prior to this [M-CH3]+ formation. However, the H/D exchange is hardly observed for the [M-CH3]+ formation in the ion source. The generated m/z 101 ions from 1+ • consist of two isomeric ions. A trimethylsilyl ion, (CH3)3Si+, at m/z 73 is generated by at least three different routes.
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COMMENTARIES
  • SNP Genotyping
    Yoshinao WADA
    2003 Volume 51 Issue 2 Pages 368-373
    Published: 2003
    Released on J-STAGE: October 16, 2007
    JOURNAL FREE ACCESS
    Mass spectrometry (MS) is proud of its high-throughput and sensitivity in the proteomic studies. However, the measurement of DNA by MS has not been in practice mainly due to its inherently large molecular size, though various applications of genetic analysis have been proposed so far. Now in the post-genome era, one of the highest demands on the genome analysis is the single nucleotide polymorphism genotyping, which is, in principle, the determination of single nucleotide substitutions at specific sites. A number of different methods using MS have been developed for this purpose, and some of those enabling multiplex analysis have advantages over other gel- or hybridization-based methods.
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  • Tohru YAMAGAKI
    2003 Volume 51 Issue 2 Pages 374-383
    Published: 2003
    Released on J-STAGE: October 16, 2007
    JOURNAL FREE ACCESS
    Lewis-type trisaccharides were analyzed by MALDI-MS. The post-source decay spectra of Lewisx(Lex) and Lewisa (Lea) trisaccharides differed each other because of the β-elimination at C-3 in the N-acetyl glucosamine of the reducing-end of Lex. The mechanism of the β-elimination in N-acetyl glucosamine of Lex was analyzed by combined in-source decay/post-source decay (ISD/PSD) measurements. The combined ISD/PSD measurements were powerful tool for the fine analysis of the mechanism of the post-source decay of the oligosaccharides. ISD/PSD measurements were also useful for the assignments of the chemical species of PSD ions.
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