A rapid fluorimetric screening method for the 1,4-benzodiazepines: Determination of their metabolite oxazepam in urine

Abstract

Oxazepam is the major metabolite screened in urine samples for the evidence of the use of benzodiazepine drugs. The methods currently used, however, are laborious and time consuming. This paper proposes an oxazepam detection method based on its hydrolysis and cyclization – a reaction catalysed by cerium (IV) in an ortho-phosphoric acid-containing medium – to form 2-chloro-9(10H)-acridinone, a strongly fluorescent molecule. The variables involved in the hydrolysis and cyclization stages were optimised. Oxazepam was detectable in the 5–900 ng mL −1 range, with a detection limit of 4.15 ng mL −1 for k = 3. The method was successfully used for the determination of oxazepam in urine samples collected at different times after the oral administration of Valium ® and Tranxilium ®.