JMSSJ On-line Abstracts, Vol.46, No.2 (1998)

Metastable and Collision-induced Dissociations of Organosilicon Compounds.

Susumu Tajima, Shigeru Mori, Takeshi Kinoshita, Hisao Nakata (Gunma National College of Technology, 580 Toribamachi, Maebashi, Gunma 371, Japan)

J. Mass Spectrom. Soc. Jpn., 46(2), 105-122 (in Japanese), 1998

Metastable and collision-induced dissociations of several organosilicon compounds have been reviewed. The fragmentation pathways of the ions of organosilicon compounds are unique and different from those of the corresponding carbon analogs.

Survey of the Recent Ionization Methods.

Kenzo Hiraoka* (Faculty of Engineering, Yamanashi University, Takeda-4, Kofu 400, Japan)

J. Mass Spectrom. Soc. Jpn., 46(2), 123-138 (in Japanese), 1998

Recent ionization methods such as electrospray, ion spray, nanoelectrospray, laser-assisted electrospray/ion spray, explosive vaporization and ionization of liquid beam by infrared laser, massive cluster impact ionization, low-energy ion impact on the van der Waals thin films, and matrix-assisted laser desorption ionization are discussed taking into account the experimental results obtained in the author's laboratory. Some prospects for the new ionization methods are given.

A Terminal Product Ion in the Fragmentation of Methyl Stearate under Electron Ionization Conditions.

Mitsuo Takayama* (Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274, Japan)

J. Mass Spectrom. Soc. Jpn., 46(2),139-142, 1998

Fragmentation of the molecular and fragment ions of methyl stearate, under 70 ev electron ionization (EI) conditions, have been studied by using collision-induced dissociation (CID) and metastable ion decay (MID) techniques. The CID and MID spectra of aged molecular ions Mi+AE quite differed from the EI mass spectrum resulted from the in-source fragmentation of initially produced molecular ions M0+AEin pattern. The CID spectra of the Mi+AE ion mainly showed peaks of m/z 255, 199, and 143 ions, while CID spectra of these 56-Da periodical fragments showed only a preferential product ion at m/z 101. CID spectra of other fragment ions also indicated that the m/z 101 ion is a terminal product. The structure of the ion at m/z 101 has been discussed.

A New Versatile Matrix for Fast Atom Bombardment Mass Spectrometry.

Mitsuo Takayama,* Hiromi Kataoka, Toyoshi Katagi, Shizuyo Horiyama, Masae Yamaki, Fukiko Hasegawa, Zeper Abliz. (Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi 274, Japan)

J. Mass Spectrom Soc. Jpn., 46(2), 143-149 (in Japanese), 1998

A new liquid matrix referred to as DTT/NBA, a 1:1 (v/v) mixture of dithiothreitol (DTT) and m-nitrobenzyl alcohol (NBA), has been prepared on the basis of a criterion for the choice of matrix in fast atom bombardment mass spectrometry. The capability of DTT/NBA was examined by comparing with those of conventional matrices from the points of durability and chemical inertness. The durability of DTT/NBA was more than ten minutes under the irradiation of fast atom beam, and the mass spectral patterns obtained little varied over the irradiation time. The DTT/NBA matrix inhibited from a degradation reaction of O-acyl oximes, while conventional matrices used here brought about a reductive degradation.