Electrooxidation and determination of the 1,4-benzodiazepine loprazolam at the carbon-paste electrode

The electrooxidative behaviour of loprazolam on a carbon-paste electrode was studied in the pH range 3.0–10.5 in aqueous solution using differential pulse, sampled direct current and cyclic voltammetry. A single oxidation peak of irreversible nature was observed in this pH range. The oxidation peak is controlled by diffusion, although adsorption phenomena may also be present. Quantitative analysis of loprazolam has been performed showing a detection limit of 1.5 × 10−7 M, and a quantitation limit of 1.7 × 10 −6 M. The precision of the determination method in terms of relative standard deviation was 3.0% for 10 determinations at a concentration level of 1.0 × 10−5 M. The method developed was applied to the determination of the compound in its formulations (Somnovit, 1 mg) obtaining errors of less than 3.8%.