Determination of nitrazepam in serum by gas-liquid chromatography. Application in bioavailability studies

A gas chromatographic method with electron capture detection has been developed for the analysis of nitrazepam in serum. N-Desmethyldiazepam is used as internal standard. Nitrazepam isolated from serum is converted by acid hydrolysis into 2-amino 5 nitrobenzophenone, which is chromatographed. Metabolites of nitrazepam (7-amino and 7-acetamido compounds) are not included in the determination. Recovery experiments showed that the method is quantitative. The limit of detection is 5 ng/ml of nitrazepam in serum. The method has been used for measuring serum concentrations of nitrazepam in bioavailability studies on subjects given a single dose of nitrazepam tablets.