Voltammetric determination of cilazapril in pharmaceutical formulations

A sensitive adsorptive stripping voltammetric method for the measurement of cilazapril in 0.04 M Britton-Robinson buffer (pH 9.0) solution was described. The method was based on the adsorptive accumulation of the drug at a hanging mercury drop electrode (HMDE), followed by differential pulse voltammetry. The response was evaluated with respect to pre-concentration time, pH effect, accumulation potential, accumulation time and scan rate. The peak potential was -0.60 V (vs. Ag/AgCl). The peak current was directly proportional to the concentration of cilazapril with a detection limit of 17.6 ng ml(-1) at an accumulation time of 10 s. The reduction process was irreversible and the wave showed adsorptive characteristics. The results were compared to those obtained using a HPLC procedure. A reversed-phase C18e column with aqueous phosphate buffer (pH 3.5; 0.125 M)-acetonitrile (67:33, v/v) mobile phase and benazapril as internal standard was used. UV detector was set at 254 nm. Results obtained in HPLC were comparable to those obtained by adsorptive stripping voltammetric method.