Determination of triazolam involving its hydroxy metabolites in hair shaft and hair root by reversed-phase liquid chromatography with electrospray ionization mass spectrometry and application to human hair analysis.

A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry has been developed for simultaneous determination of triazolam and its hydroxy metabolites in hair. After the addition of deuterium-labeled 1-hydroxymethyltriazolam as an internal standard, the analytes in hair shaft and hair root samples were extracted with a basic medium, CH(2)Cl(2):MeOH:28% NH(4)OH (20:80:2) at room temperature overnight. The chromatographic separation of the analytes was achieved using a semimicro HPLC column (3-microm particle size; 100 x 2.0-mm i.d.) by gradient elution with acetonitrile in water containing 1% acetic acid as eluent. The mass spectrometer was operated in selected-ion monitoring mode at quasi-molecular ions [M+H](+) of triazolam and its metabolites. The method has been applied to determine the incorporation of triazolam and its metabolites into the hair shafts and hair roots of Dark Agouti rats administered 3 or 6 mg/kg triazolam intraperitoneally twice a day for 5 days. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were incorporated into the hair shafts and the hair roots. The concentration of 4-hydroxytriazolam was the highest of all compounds detected. An unknown substance considered to be 1,4-dihydroxytriazolam also appeared in the hair samples. The structural elucidation was performed with online HPLC-MS after acetylation of the substance with acetic anhydride and pyridine. The time course studies of triazolam and the metabolites in both rat hair roots and plasma were carried out after single intraperitoneal administration of triazolam. The concentrations of triazolam and the metabolites in the hair roots reflected those in the plasma. The proposed method using selected-reaction monitoring was applied to the determination of triazolam and the metabolites in human hairs of a triazolam addict. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were identified in the black hair shafts, whereas only triazolam was detected in the hair roots and the white hair shafts. This is the first report on the detection of triazolam and its metabolites in human hairs. Copyright 2001 Academic Press.