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Study of selected ions in the ammonia desorption chemical ionization mass spectra of peracetylated gentiobiose and two isotopically labelled peracetylated gentiobioses
Author(s) -
Peltier John M.,
Smith Richard W.,
Maclean David B.,
Szarek Walter A.
Publication year - 1992
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.1210270108
Subject(s) - chemistry , moiety , fragmentation (computing) , mass spectrum , ammonia , ion , chemical ionization , mass spectrometry , medicinal chemistry , nucleophile , ionization , stereochemistry , organic chemistry , catalysis , chromatography , computer science , operating system
The ammonia desorption chemical ionization (NH 3 ‐DCI) mass spectra of peracetylated gentiobiose (1) and two isotopically labelled gentiobioses (2 and 3) were examined. Compound 2 is labelled with trideuteroacetyl groups in the non‐reducing moiety and 3 with trideuteroacetyl groups in the reducing moiety. It is shown that the [M + NH 4 – 42] + ion is not formed direct from [M + NH 4 ] + by loss of ketene but appears to be formed by way of a nucleophilic acyl substitution reaction resulting in a neutral species which complexes with NH 4 + . The disaccharides undergo cleavage at either side of the glycosidic oxygen joining the two sugar residues, a process which is accompanied by addition of H or CH 3 CO to afford neutral species which complex with NH 4 + . The structures of the ions resulting from H transfer have been inferred by comparison of their mass‐analysed ion kinetic energy (MIKE) spectra with MIKE spectra of the [M + NH 4 ] + ions of compounds of established structure. A ring fragmentation reaction of 1, 2 and 3 is reported.