An automated screening system for benzodiazepines in human urine Original Research Article

A rapid flow system for determining the presence or absence of benzodiazepines in human urine has been developed and optimized. The system is based on the diazotization of the analytes in a pre-hydrolyzed samples at pH<1, followed by the formation of dyes with 1-naphthol at pH>12. The dyes are retained and washed on a XAD-2 minicolumn, and immediately eluted with 3 M NaOH in ethanol/water. A simple photometer is used at λ=550 or 600 nm to monitor the overall analyte content. The reliability of the proposed method for the benzodiazepines is demonstrated in simple chemometric terms, using four concentration levels (between 0.5 and 2 times the detection limit) and oxazepam as model benzodiazepine. The method is highly selective and a sensitive enough for detecting benzodiazepines in urine.