Hair analysis for nordiazepam and oxazepam by gas chromatography negative-ion chemical ionization mass spectrometry

A procedure is presented for the identification of nordiazepam and its metabolite, oxazepam, in human hair. The method involves decontamination of hair with dichloromethane, incubation in phosphate buffer (pH 7.6) in the presence of deuterated internal standards, liquid-liquid extraction, derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide plus 1% trimethylchlorosilane and gas chromatography-mass spectrometry using negative-ion chemical ionization with methane. Among thirty samples obtained from polydrug abusers, thirteen tested positive for nordiazepam, in the range 0.25-18.87 ng/mg. Five samples were also positive for oxazepam, in the range 0.11-0.50 ng/mg.