Rapid gas chromatographic measurement of diazepam and its metabolites desmethyldiazepam, oxazepam, and 3-hydroxydiazepam (temazepam) in small samples of plasma.

A rapid method was developed for the determination of diazepam, desmethyldiazepam, oxazepam, and 3-hydroxydiazepam (temazepam) in human plasma using electron capture gas chromatography. Following a single extraction with benzene from 0.2 ml plasma, diazepam and its metabolites were quantitated on a SP-2250 column with medazepam as internal standard. The method has a sensitivity limit of 4 ng diazepam, oxazepam, and desmethyl-diazepam, and 15 ng 3-hydroxydiazepam per ml of plasma.