The role of self-protonation under direct GC-MS determination of amphetamine hydrochloride

Abstract

SummaryWe studied the possibility of direct GC-MS determination of amphetamine hydrochloride. In order to avoid the double peak we determined the optimal injector temperature (260 ~ and heating rate (40 ~ min-1). In the direct analysis of amphetamine hydrochloride containing samples, calibration for fragment m/z = 59 (originating from amphetaminium ion fragmentation; the calibrating agent is amphetamine hydrochloride) gave better results than calibration for m/z = 44 (derived from both free amphetamine and amphetaminium ion; calibration agents were amphetamine or amphetamine hydrochloride). We also compared the mass spectra of amphetamine and amphetamine hydrochloride taken by ion-trap GC-MS. The fragmentation pathway of the amphetamine and amphetaminium ion was different. The main fragmentation path was cleavage of the C-C bond at benzyl position for the free base or between the phenyl group and the aliphatic moiety, in the case of free base and amphetaminium ion, respectively