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Volume 49 (2001)
- Issue 6 Pages 219-
- Issue 5 Pages 175-
- Issue 4 Pages 135-
- Issue 3 Pages 83-
- Issue 2 Pages 41-
- Issue 1 Pages 1-
Volume 49, Issue 4
Displaying 1-4 of 4 articles from this issue
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INTEGRATED PAPER
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Kazunaka ENDO2001 Volume 49 Issue 4 Pages 135-143
Published: 2001
Released on J-STAGE: October 16, 2007
JOURNAL FREE ACCESSThe cleavage sites of representative polymers in time-of-flight(TOF)- and static(S)-secondary ion mass spectrometry (SIMS) can be estimated from the two-center bond energies of the electric neutral model oligomers by semiempirical MO calculations using the AM1 method in MOPAC software. The cleavage of the intramolecular bonds may be classified into three cases; a) the scission can occur in any bonds [polyethylene, poly-(vinyl methyl ether), polyacrylonitrile, poly(vinyl alcohol)], b) the cleavage of the main chain occur in any bonds, after pendant groups break first [poly(vinyl chloride), poly(acrylamide)], c) the main chain carbons with the pendant group break in any bonds of the main chain [poly(vinyl floride), poly(tetrafluoroethylene)]. Examples of the cleavage are also used in secondary positive-ion fragment spectra of conductive polymers. Furthermore, we analyze the decomposition process of nitrocellulose (NC) due to X-ray induced surface damage by the MO calculations using the electric neutral dimer model. The scission of NO2 groups in the NC is confirmed from the TOF-SIMS measurement.View full abstractDownload PDF (690K)
REGULAR PAPERS
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Shigeo HAYAKAWA, Masayoshi MORI, Nobuaki WATANABE, Keizo FUJII, Kazuo ...2001 Volume 49 Issue 4 Pages 144-149
Published: 2001
Released on J-STAGE: October 16, 2007
JOURNAL FREE ACCESSA trapezoidal peak shape of dissociative ions is observed in the charge inversion mass spectra. The relation between the kinetic energy release (KER) and the peak shape was simulated. Dissociation with a specific KER value having very narrow distribution for both ionic and neutral species affords the trapezoidal peak shape in a mass spectrum. The KER value was evaluated from the full width at half maximum (FWHM) of the trapezoidal peak associated with the CH3O- ions formed from CH3OH+ ions in the charge inversion mass spectrum. The KER value showed the good agreement with that evaluated from the velocity distribution of H atom formed from the photo-dissociation of neutral methanol. This agreement demonstrated that the excited neutral methanol dissociated predominantly into the methoxy radical and the hydrogen atom, and that charge inversion mass spectrometry gave the dissociation of energy-selected neutral species.View full abstractDownload PDF (527K) -
Mayuko ISHIDA, Jun HAYAKAWA, Masayoshi IMAGAWA, Ryo TAGUCHI2001 Volume 49 Issue 4 Pages 150-160
Published: 2001
Released on J-STAGE: October 16, 2007
JOURNAL FREE ACCESSA fast and sensitive analytical method of phospholipids by capillary liquid chromatography/electrospray ionization-mass spectrometry was applied to the analysis of individual molecular species of phospholipids in mammalian cells with or without previous treatment with phospholipases. Using a quadrupole mass spectrometer, we selected a simultaneous analysis method under four different functions for detection of positive and negative molecular related ions as well as fragment ions. In the analysis of the elution patterns of the phospholipids, a two-dimensional map revealed to be very useful. By the treatment with phospholipases A or phospholipases C, significant decrease of substrate phospholipids in extracted lipid mixture or cells. Increase of products, such as lyso-phospholipids, and diglycerides or ceramides were effectively determined. Especially by the treatment with PLA1 or PLA2, accumulation of specific molecular species of lyso-phospholipids, either unsaturated or saturated, were respectively detected. Application of anion exchange column was also examined for effective separation and identification of acidic phospholipids, such as phosphatidylinositol, phosphatidyl-glycerol, phosphatidylserine, phosphatidic acid, and their lyso-forms. Analyses of these acidic lyso-phospholipids are very important to elucidate their function as lipid mediators.View full abstractDownload PDF (1005K) -
Yoshiyuki MOCHIDA, Gorou ARAI, Shigeo NAKAMURA, Masahiko TSUCHIYA2001 Volume 49 Issue 4 Pages 161-170
Published: 2001
Released on J-STAGE: October 16, 2007
JOURNAL FREE ACCESSAppropriate solvents and additives were investigated for liquid ionization (LPI) mass spectra of dialkylperoxides having one peroxy group, such as di-t-butyl peroxide (BB), t-butyl cumyl peroxide (BC), dicumyl peroxide (CC), and having two peroxy groups, such as 2,5-dimethyl-2,5-di(t-butyl peroxy)hexane (BAB), α,α′-bis-(t-butyl peroxy)diisopropyl benzene (BPB), 2,5-dimethyl-2,5-di(t-butyl peroxy)hexyne-3 (BYB). When each sample was dissolved only in a solvent (e.g., ethanol, hexane, octane, or toluene), abundant hydrated protonated molecules [M+H+H2O]+ were observed for all samples, but peaks corresponding to protonated molecules [M+H]+ were weak, except for BAB. Addition of butanol to alkane (solvent) increased the abundance of [M+H]+, with decrease of [M+H+H2O]+ for BAB, BPB, and BYB. For these compounds (having two peroxy groups), the addition of butanol (BuOH) to the suitable solvent, such as toluene, was effective for producing dominant adduct ions [M+H+BuOH]+ with few [M+H+H2O]+. The addition of ethylamine (EA) to any solvent examined was also effective for producing adduct ions [M+H+EA]+ for all dialkylperoxides. It is interesting that BB having a symmetric structure gave dominant molecular ions M+· even in the ionization condition like LPI. The addition of p-cresol (PC) to a suitable solvent was useful for BB and BAB (both symmetric structures) to produce dominant molecular adduct ions like [M+PC]+·. LPI-MS is useful not only for determining relative molecular mass of dialkylperoxides but also for investigating the effects of solvents and various kinds of additives.View full abstractDownload PDF (665K)
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