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Differences between collisionally activated and electron‐transfer dissociations found for CH 2 X 2 (X = Cl, Br, and I) by using alkali‐metal targets
Author(s) -
Sasaki Tomohiro,
Matsubara Hiroshi,
Hayakawa Shigeo
Publication year - 2008
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1458
Subject(s) - chemistry , ion , dissociation (chemistry) , alkali metal , halogen , analytical chemistry (journal) , mass spectrum , spectral line , metal , electron ionization , ionization , alkyl , physics , organic chemistry , chromatography , astronomy
High‐energy collisionally activated dissociation (HE‐CAD) and high‐energy electron‐ transfer dissociation (HE‐ETD) on collisions with alkali‐metal targets (Cs, K, and Na) were investigated for CH 2 X 2 + (X = Cl, Br, and I) ions by tandem mass spectrometry (MS/MS). In the HE‐CAD spectra observed, peaks associated with CH 2 X + ions formed by a loss of a halogen atom are always predominant regardless of precursor ions and target metals. The observation of the predominant CH 2 X + ions is explained by the lowest energy levels of the fragments of CH 2 X + + X among the possible fragment energy levels and internal‐energy distribution in HE‐CAD. In the charge‐inversion spectra, relative peak intensities of the negative ions formed by HE‐ETD strongly depend on the precursor ions and the target metals. While the CHCl 2 − ion was predominant in the spectra of CH 2 Cl 2 + regardless of target species, the most intense peaks in those of CH 2 Br 2 + and CH 2 I 2 + were ascribed to either Br − or CH 2 Br − and either I − or I 2 − , respectively, depending on the target metals. The dependence of the relative intensities of the fragment ions by HE‐ETD on the precursor ions and target species are discussed on the basis of the energy levels of the neutral fragments and the narrow internal‐energy distribution resulting from the near‐resonant neutralization. It was demonstrated that HE‐ETD using the alkali‐metal targets provided rich information on the dissociation of the neutral species. Copyright © 2008 John Wiley & Sons, Ltd.