Fragment-molecule adduct ion formation in the mass spectra of cyclic N-acetylamines and related nitramines

Mass spectra of seven related N-heterocyclics, introduced by direct exposure probe, were determined in electron impact (EI) and positive- and negative-ion chemical ionization (PCI and NCI) modes. Proton adducts were the predominant molecular ion species in the EI and PCI modes. In addition, a variety of fragment–molecule adduct ions were observed for each compound in one or more of the modes. The propensity of 1,3,5-trinitrohexahydro-1,3,5-triazine for fragment–molecule adduct formation was high in all three ionization modes. Fragmentation processes were documented by collision-induced dissociation experiments.