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 50, Issue 6
Displaying 1-9 of 9 articles from this issue
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REGULAR PAPERS
  • Negative Chemical Ionization Mass Spectrometric Study on the Dissociative Electron Attachment to Halogenated Ethane
    Seiko NAKAGAWA
    2002 Volume 50 Issue 6 Pages 286-289
    Published: 2002
    Released on J-STAGE: October 16, 2007
    DOIhttps://doi.org/10.5702/massspec.50.286
    JOURNAL FREE ACCESS
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    The temperature dependence for the formation of negative ions from Cl2BrC-CBrCl2, FClBrC-CBrF2, and ClBr2C-CF3 was studied using negative chemical ionization mass spectrometry. Halide ions and halogen molecular anions were observed. The intensity ratios between the halide ions and halogen molecular anions were almost equal to F2BrC-CBrF2. Halogen molecular anions are produced from halogen atoms presented by each C atom: the four-center elimination. The temperature dependence of the ion intensity ratios, Br-/Cl- and Br2-/BrCl-, suggests that the strength of the bonding energy of the C-Cl relative to C-Br increases in the order of Cl2BrC-CBrCl2<FClBrC-CBrF2<ClBr2C-CF3.
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  • Matrix Effects on the Chiral Recognition Determined by the Relative Peak Intensity of Diastereomeric Host-Guest Complex Ions Using the FAB Mass Spectrometry/Enantiomer Labeled Guest Method
    Motohiro SHIZUMA, Hitoshi YAMADA, Hiroshi ADACHI, Yoshio TAKAI, Tokuji ...
    2002 Volume 50 Issue 6 Pages 290-295
    Published: 2002
    Released on J-STAGE: October 16, 2007
    DOIhttps://doi.org/10.5702/massspec.50.290
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    The FAB mass spectrometry (MS)/enantiomer labeled (EL) guest method is one of the useful technique to easily evaluate chiral discrimination ability of a chiral host (H) toward chiral guests (GR+, GS-dn+). In this paper, the matrix dependency of the relative peak intensity (IRIS) of the diastereomeric host-guest complex ions [(H+GR)+ and (H+GS-dn)+] was investigated (host, MeFruNys; guest, Phe-O-iPr+). The IRIS values of spectra measured using NBA, NPOE, and DTDE matrices agreed almost with the ratio of concentrations of the complex ions calculated from the association constants (KR and KS) in chloroform at 298 K. While, the IRIS values of spectra using glycerol matrix reached almost unity. It was assumed that the IRIS values depend upon the matrices used since the difference of solvation ability of the matrices affects the actual concentration of the guest concerning in the complexation. And then, it was recommended that NBA is the best matrix for chiral recognition mass spectrometry studies.
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  • Study of Electron Impact Ionization Cross-sections of Sodium-containing Molecules
    Jintao HUANG, Tomohiro FURUKAWA, Kazumi AOTO, Michio YAMAWAKI
    2002 Volume 50 Issue 6 Pages 296-300
    Published: 2002
    Released on J-STAGE: October 16, 2007
    DOIhttps://doi.org/10.5702/massspec.50.296
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    Electron impact ionization is a common way to provide positive ions for mass spectrometry. For most of molecular vapor species, however, experimental values of their electron impact ionization cross-sections are so limited that theoretic estimations become necessary. It is found that classic model such as additive rule or its modified version is no longer valid near the ionization threshold. Knowledge in this area is important for alkaline metals like sodium because their molecules may reach the maximum cross-section just a few eV above the ionization potential and easily crack in higher incident energies. A Binary-Encounter-Bethe (BEB) model developed by NIST was employed to calculate the cross-sections of NaO, NaOH, Na2, and Na2O molecules. The total ionization cross-section is computed from partial cross-sections of molecular orbitals. Gaussian and GAMESS code were employed to calculate the necessary molecular orbital parameters in the ground state. Calculated cross-sections were plotted as a function of electron impact energy. Reliability of the data predicted by BEB model was investigated by measuring corresponding ionization efficiency curves for some of the molecules. It was found that I(E)/Imax is generally equal to σ(E)/σmax within 15% in the testing range from 5 to 30 eV for sodium-containing molecules. It indicates that the BEB predictions seem correct at low electron incident energies.
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NOTES
INTEGRATED PAPER
  • Development of Quantitative Chiral Recognition Mass Spectrometry
    Masami SAWADA
    2002 Volume 50 Issue 6 Pages 311-329
    Published: 2002
    Released on J-STAGE: October 16, 2007
    DOIhttps://doi.org/10.5702/massspec.50.311
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    The developments of our quantitative chiral recognition studies in the host-guest complexations between chiral crown ethers and chiral amino acid esters by FAB, ESI, and MALDI mass spectrometry have been described. Both the enantiomer labeled (EL)-guest method and the EL-host method, which had been previously proposed by us, were successfully advanced. The relative peak intensity (IRIS) values of the diastereomeric host-guest complex ions appeared in mass spectra were especially noted, and their use to chiral recognition was illustrated. Generally, the former method was used to chiral recognition ability-determination of a given host, and the latter one was used to enantiomeric excess (e.e.)-determination of a given guest. Through the manuscript, emphasis has been put on the finding that one can detect correctly the concentration ratio of the two diastereomeric host-guest complex ions formed in a matrix solution by FAB mass spectrometry and then, that FABMS is a powerful tool for detecting chiral host-guest interactions in the host-guest complexation systems. Recent ,e.e.-determination methods by ESI mass spectrometry etc. were also summarized.
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REGULAR PAPER
  • Polar Derivatization of 5α-Dihydrotestosterone and Sensitive Analysis by Semimicro-LC/ESI-MS
    Yumiko NAKAGAWA, Yutaka HASHIMOTO
    2002 Volume 50 Issue 6 Pages 330-336
    Published: 2002
    Released on J-STAGE: October 16, 2007
    DOIhttps://doi.org/10.5702/massspec.50.330
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    Polar derivatization method for electrospray ionization mass spectrometry (ESI-MS) was developed and applied to the sensitive analysis of 5α-dihydrotestosterone (DHT) in prostate and plasma. Rat prostate was dissolved with alkaline solution and DHT in the prostate was extracted by solid phase extraction, and derivatized to the N-methylpyridinium-DHT as a polar derivative. The N-methylpyridinium derivative of DHT was purified by solid-phase extraction using Bond Elut C18, and determined by a semimicro-LC/ESI-MS with selected reaction monitoring (SRM). Linear responses of the N-methylpyridinium derivative of DHT were observed for analyte concentration from 5 to 100 pg/tube. DHT values were 12.0±3.8 ng/g tissue in rat prostates, 171.7±127.2 pg/mL in rat plasma and 286.2±123.5 pg/mL in human plasma.
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COMMUNICATIONS
  • The Characteristics of In-source Decay in Mass Spectrometric Degradation Methods
    Hydrogen-Attachment Dissociation (HAD)
    Mitsuo TAKAYAMA
    2002 Volume 50 Issue 6 Pages 337-349
    Published: 2002
    Released on J-STAGE: October 16, 2007
    DOIhttps://doi.org/10.5702/massspec.50.337
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    In-source decay (ISD) combined with matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometer (TOF MS) has been described by comparing with conventional mass spectrometric degradation (MSD) methods such as collision-induced dissociation (CID) and post-source decay (PSD). The ISD characteristic is the formation of c- and (z+2)-ions originated from the N-Cα bond cleavage on the peptide backbone, while the CID and PSD processes are the CO-NH bond cleavage which brings about b- and y-ion. Furthermore, the ISD processes occurring with 337 nm laser photon irradiation for peptide or protein proceed resulting in the formation of hyper-valent radical species via intermolecular hydrogen transfer between matrix and analyte molecules following the non-ergodic N-Cα bond cleavage. The non-ergodic N-Cα bond cleavage occurs in the MALDI ion source within nanosecond order, as an α-cleavage initiated with radical site at the carbonyl carbon. The MALDI-ISD method has been applied to three peptides and five proteins.
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  • Time-of-Flight Studies of Secondary Ions Produced by 400 eV He+ Ion Impact on Ar, Kr, and Xe Thin Films at 8 K
    Makoto WATANABE, Daisuke EGUCHI, Tetsuya SATO, Kenzo HIRAOKA
    2002 Volume 50 Issue 6 Pages 350-352
    Published: 2002
    Released on J-STAGE: October 16, 2007
    DOIhttps://doi.org/10.5702/massspec.50.350
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    Secondary ions produced by 400 eV He+ ion impact on Ar, Kr, and Xe thin films deposited on a silicon substrate at 8 K were measured as a function of film thickness using a time-of-flight secondary-ion mass spectrometer. For Ar, the cluster ions Arn+ up to n=4 as well as the monomer ion (n=1) were observed and they showed characteristic film-thickness dependence with increase of the film thickness up to ~200 monolayers. This is due to the momentum transfer in the elastic collision between the incident He+ ion and the matrix Ar atoms and also to the relaxation of electronic excitations (e.g., holes and excitons) to phonons resulting in the film erosion. In contrast, neither dimer nor cluster ions were detected for solid Kr and Xe films. This is due to the less efficient momentum transfer in the elastic collision between He+ and Rg's (Rg=Kr and Xe) and also to the efficient electronic energy migration in solid Kr and Xe. The C+ ions originating from the carbonic contaminants on the silicon substrate were found to be sensitized by the deposition of rare gas films. The penetration depths of the primary ion He+ through the rare gas films increase in the order of Ar<Kr<Xe.
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