Simultaneous assay of triazolam and its main hydroxy metabolite in plasma and urine by capillary gas chromatography.

A gas--liquid chromatographic method for the simultaneous determination of triazolam and its major hydroxy metabolite (1-hydroxymethyltriazolam) in human plasma and urine is described. After addition of two internal standards to the biological fluid, extraction at pH 9, acid washing, back-extraction, and derivatization, the analysis was performed on a wall-coated superior capacity open-tubular (WSCOT) CP-Sil 5 capillary column with electron-capture detection. The detection limit was 0.1-0.2 ng/ml; reproducibility was about 6-7% for plasma concentrations below 1 ng/ml. No interference from other possible minor hydroxy metabolites of triazolam was found. Gas chromatography coupled with mass spectrometry validated the chromatographic results. The method was successfully applied to plasma specimens collected from healthy human volunteers following a single intravenous administration of 1 mg of triazolam or 1-hydroxymethyltriazolam.