Simultaneous screening and quantitative analysis of benzodiazepines by dual-channel gas chromatography using electron-capture and nitrogen-phosphorus detection.

A rapid twin-column gas chromatographic method for the simultaneous screening and determination of commonly prescribed benzodiazepines from plasma and whole blood is presented. Identical fused-silica SE-54 columns were inserted in a common split-splitless injector and connected to nitrogen-phosphorus and electron-capture detectors. By combining these specific and sensitive detectors considerable and accurate chromatographic information was obtained in a single run. The drugs were extracted from 1 ml of buffered plasma or blood with n-hexane-dichloromethane (70:30) and analysed without derivatization. Flurazepam was used as internal standard. The method was reproducible enough to permit reliable quantitation of plasma diazepam, nordiazepam, oxazepam, lorazepam, chlordiazepoxide, temazepam, midazolam, alprazolam, clobazam, norclobazam, adinazolam, flunitrazepam, bromazepam, triazolam, nitrazepam and clonazepam within 12 min.