Comparison of quadrupole and (quadrupole) ion-trap mass spectrometers for the analysis of benzodiazepines

GC-MS with on-column injection is evaluated for the analysis of benzodiazepines. A standard mixture of five benzodiazepines (ketazolam, flunitrazepam, flurazepam, alprazolam and triazolam) was used to compare the applicability of different types of mass spectrometers. Using an ion-trap mass spectrometer excessive peak tailing was observed on the late-eluting peaks. Injections on four other ion-trap systems, both with internal or external ionisation, yielded similar results. However, all peak shapes became acceptable when injections were performed on a quadrupole system. The results obtained on three other quadrupole mass spectrometers confirmed this observation. These data strongly suggest that a quadrupole instrument is more suitable than an ion-trap one for the analysis of some benzodiazepines. (C) 1998 Elsevier Science B.V. All rights reserved.