Negativeion Chemical Ionization of Amphetamine Derivatives

Abstract

The negative-ion chemical ionization (NICI) mass spectra of the heptafluorobutyryl (HFB) and pentafluorobenzoyl (PFBz) derivatives of several amphetamines and N-substituted amphetamines were obtained. The HFB derivatives of amphetamine and its ring-substituted congeners were each found to undergo predominant loss of one molecule of hydrogen fluoride, while the corresponding PFBz derivatives each underwent sequential loss of two molecules of hydrogen fluoride followed by the loss of either a methyl or an aryl group. The HFB derivatives of the N-substituted amphetamines were found to undergo sequential loss of four molecules of hydrogen fluoride while the corresponding PFBz derivatives produced high-abundance molecular ions. NICI mass spectra of deuterium-labelled amphetamine derivatives were obtained and the order of hydrogen elimination was studied. These findings explain previous observations of hydrogen fluoride loss by the amphetamine derivatives and define potential applications of NICI mass spectrometry to the analysis of these compounds.