FAST-ATOM-BOMBARDMENT AND ELECTROSPRAY TANDEM MASS-SPECTROMETRY - SOME FRAGMENTATION REACTIONS IN CYCLIC NITRAMINES STUDIED USING COLLISION-INDUCED DISSOCIATION

The initial fragmentation pathways of some cyclic nitramines containin g nitroguanidine and/or secondary nitramine groups were identified by fast atom bombardment (FAB) ionization mass spectrometry. Their partia lly nitrated analogues were analyzed as nitric acid salts using both F AB and electrospray (ES) ionization mass spectrometry, The ES techniqu e gave simple mass spectra dominated by the more diagnostic higher mol ecular-mass species, which were ideal for tandem mass spectrometry (MS /MS) studies, Fragment-molecule adduct ions of the type [MH+NO2](+) an d/or [MH+NO](+) were observed in the FAB spectra in some cases, Fragme ntation processes of these and the protonated molecules, together with some fragment ions, were elucidated, The main fragmentation processes were the loss of H2O, NO2 group(s) and to a lesser extent NO, Minor t ransitions involving ring fragmentations were more favorable for the n itric acid salts than their more highly nitrated analogues.