Abstract
Diazepam, oxazepam and N-demethyldiazepam were determined by high performance liquid chromatography using a radially compressed C18 column and an aqueous methanolic mobile phase. The chromatographic separation was completed within 10 min. The drugs were recovered from [human] serum by extraction with hexane:ethyl acetate 70:30, v/v [vol/vol]. The method was linear in the range 50-1600 ng/ml for all drugs. Coefficients of variation were < 6.2% for 2 studied concentration levels.