Determination of diazepam and oxazepam using high-performance liquid chromatography and fourth-derivative spectrophotometric techniques

Abstract

Accurate and very precise HPLC and fourth-derivative ultraviolet spectrophotometric methods for the determination of diazepam and oxazepam in dosage forms are described. The methods are capable of distinguishing the intact drugs from their hydrolytic degradation products at 6 M hydrochloric acid. Mean recoveries for mixtures containing the drugs and their degradation products were found to be 101.3 ± 2.5 and 101.4 ± 1.8% using the HPLC procedure and 100.8 ± 2.0 and 101.0 ± 2.7% using the fourth-derivative spectrophotometric technique for diazepam and oxazepam, respectively. The reported procedures have been successfully applied to monitoring either diazepam or oxazepam in pharmaceutical formulations.