巻号一覧
50 巻 (2002)
- 6 号 p. 286-
- 5 号 p. 213-
- 4 号 p. 173-
- 3 号 p. 100-
- 2 号 p. 52-
- 1 号 p. 1-
50 巻, 4 号
選択された号の論文の5件中1～5を表示しています
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総合論文
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中田 尚男2002 年 50 巻 4 号 p. 173-188
発行日: 2002年
公開日: 2007/10/16
ジャーナル フリーA rule of mass shift, which accounts for mass shifts in fragmentations of even-electron organic ions, is exemplified in detail. The term “mass shift” is defined as a mass difference between the mass of an observed ion and the mass calculated from the corresponding part of the structural formula of a sample molecule. According to the nature of the cleaved bond, the mass shift is either 0, +1, +2, or even +3 for positively charged fragment ions, and 0, -1, or -2 for negative ions. Rationalization of the rule is made on the basis of structural requirement of stable even-electron organic ions. The rule is shown to be valid not only for ordinary reactions of positive or negative ions but also for collision-induced dissociations and charge-remote fragmentations. Some mechanistic implication of fragmentations related to the rule is also discussed.抄録全体を表示PDF形式でダウンロード (1467K)
報文
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Kenzo HIRAOKA, Yoshiki ASAKAWA, Kazuhiro UEDA, Asuka HORI, Tohru SAKAI ...2002 年 50 巻 4 号 p. 189-192
発行日: 2002年
公開日: 2007/10/16
ジャーナル フリーA laser spray interface for use in liquid chromatography/mass spectrometry (LC/MS) has been investigated with respect to the degradation of a thermally labile compound, ribostamycin. It was confirmed that few fragment ions were formed when the laser beam was focused to the center of the stainless steel capillary. When the laser beam was slightly off-centered, the sample ions suffered from the thermal degradation by the heated wall of the stainless steel capillary. A feasible observation of fragment ions for the thermally labile compounds by the wall heating would be useful for the structural elucidation of the sample molecules.抄録全体を表示PDF形式でダウンロード (424K)
ノート
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Susumu TAJIMA, Osamu SEKIGUCHI, Satoshi NAKAJIMA, Nico M.M. NIBBERING2002 年 50 巻 4 号 p. 193-198
発行日: 2002年
公開日: 2007/10/16
ジャーナル フリーThe unimolecular metastable decompositions of bis(2,2,2-trifluoroethyl) ether, CF3CH2OCH2CF3 (1), and ethyl 2,2,2-trifluoroethyl ether, CH3CH2OCH2CF3 (2), induced by electron ionization, have been investigated by mass-analyzed ion kinetic energy (MIKE) spectrometry and energy-dependent collision-induced dissociation (CID) spectra in conjunction with thermochemical data. In the metastable time window, the molecular ions of 1 decompose into the ions at m/z 113 by the loss of CF3 and m/z 83 by the consecutive losses of CF3 and CH2O, while those of 2+ • decompose into the ions at m/z 113 and m/z 59 by the elimination of CH3 and CF3 , respectively. The decomposition of the latter fragment ion is similar to that of the m/z 59 ion from the corresponding fluorine-free analogue, diethyl ether, CH3CH2OCH2CH3 (3), that is, fragment ions m/z 41 and m/z 31 are observed, which correspond to the competitive losses of H2O and C2H4, respectively. The metastable ions m/z 113 from 1+ • and 2+ • decompose in a variety of ways: in addition to the fragment ion m/z 65, which is generated by the elimination of CHFO, four other fragment ions with m/z 83, 63, 61, and 31 are observed , which correspond to the competitive losses of CH2O, (CH2O+HF), CH2F2, and C2HF3 (or C2H4F2O), respectively.抄録全体を表示PDF形式でダウンロード (758K) -
Tomomi KANI, Susumu NOHDA2002 年 50 巻 4 号 p. 199-203
発行日: 2002年
公開日: 2007/10/16
ジャーナル フリーIt has been established that a new filament loading scheme for lead isotopic analysis using thermal ionization mass spectrometry, so called “bead method,” which gives stable ion beam and high reproducibility. Two minor modifications to this scheme are presented in this paper; finer colloidal silicic acid is used instead of silica-gel, and flash heating is performed in nitrogen environment to prevent excess oxidation of filament. We report lead isotopic compositions of the NIST lead standard SRM 981, BCR-1, and GSJ standard rock samples using the present method.抄録全体を表示PDF形式でダウンロード (510K)
速報
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Tohru YAMAGAKI, Hiroshi NAKANISHI2002 年 50 巻 4 号 p. 204-207
発行日: 2002年
公開日: 2007/10/16
ジャーナル フリーWe used norharmane (9H-pyrido[3,4-b]indole) as a matrix for negative-mode ionization of neutral oligosaccharides in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). In-source decay (ISD) fragmentation occurred, producing fragment ions [(M-C4H8O4)-H]- in negative-mode linear MALDI-MS. The ISD product ion [(M-C4H8O4)-H]- of maltoheptaose was predominantly observed but deprotonated molecule was not. In the MALDI mass spectrum of cellohexaose, the ISD product ion [(M-C4H8O4)-H]- was observed, as was deprotonated molecule [M-H]-. In positive-mode MALDI-MS spectra of oligosaccharides, these ISD product ions were not observed. In cyclomaltooligosaccharides of cyclodextrins (CD), only deprotonated molecules [M-H]- were observed clearly and ISD product ions were not seen in negative-mode MALDI-MS. The result of sugar branched cyclodextrin of glucosyl-βCD was the same. The ISD product ion [(M-C4H8O4)-H]- of maltoheptaose would thus occur at the reducing end and corresponded to 2, 4A fragmentation. In the post-source decay (PSD) fragment spectra of cyclodextrins, PSD product ions [(M-C4H8O4)-H]- produced by 2, 4A and Z cleavage were observed. The formation of PSD product ions [(M-C4H8O4)-H]- of cyclodextrins would thus relate to that of ISD product ions of linear oligosaccharides in negative-mode MALDI-MS.抄録全体を表示PDF形式でダウンロード (421K)
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