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Formation of M +. ions under matrix fast atom bombardment conditions: Does charge exchange reaction occur?
Author(s) -
Takayama Mitsuo,
Iwamura Michiko,
Fuchibe Shohaku
Publication year - 1994
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210291105
Subject(s) - ion , chemistry , mass spectrum , fragmentation (computing) , electron ionization , spectral line , fast atom bombardment , ionization , polyatomic ion , analytical chemistry (journal) , chemical ionization , mass spectrometry , atom (system on chip) , physics , organic chemistry , chromatography , astronomy , computer science , operating system , embedded system
The formation of molecular ions, M +. , under fast atom bombardment (FAB) conditions using a liquid matrix was examined by using a new type of synthesized compounds in which preferential M +. peaks appear in their FAB spectra. The FAB spectra were compared with the corresponding mass spectra obtained by the electron impact (EI) ionization, chemical ionization (CI) and charge‐exchange ionization (CEI) methods. All of the spectra showed preferential peaks of M +. ion and a characteristic intense fragment ion peak originating from a β‐fission. The FAB spectra were similar in the fragment ions appearing in the EI spectra and were very similar in the fragmentation pattern to the CEI spectra using Ar +. and Xe +. as the reagent ions. Further, the FAB spectra did not show any doubly charged ion peaks, while the 70 eV EI spectra showed the peaks of doubly charged molecular and/or fragment ions. The isobutane CI spectra of the synthesized compounds suggested that the formation of M +. ions occurred through the CE reaction with isobutane ion, C 4 H 10 +. , and the CI spectra showed a marked intense fragment ion peak originating from the β‐fission which seemed to occur characteristically in CEI processes. The results obtained suggested that the formation of M +. ions under matrix FAB conditions occurred mainly by CE reactions between the analytes M and matrix molecular ions B +. and/or fragment ions b +. .