Sensitive and simple gas chromatographic–mass spectrometric determination for amphetamine in microdialysate and ultrafiltrate samples

A gas chromatographic–mass spectrometric (GC–MS) method is described for the measurement of amphetamine (AMP) using negative chemical ionization (NCI) mode. Without prior extraction AMP was derivatized with 2,3,4,5,6-pentafluorobenzoyl chloride (PFBC) and simultaneously extracted into toluene. The toluene extract was injected directly into GC–MS equipped with a HP-1 capillary column. The method is simple and more sensitive than most of the previously published methods. The limit of quantification of amphetamine is 25 pg (1.4 pg on column) with a very limited sample volume (25 μl). The within-day precision was from 1.7 to 5.1% and between-day precision was from 2.2 to 7.3%. The method has been used for the measurement of several thousand microdialysate and ultrafiltrate samples and proven reliable.