Electroanalytical Determination of Captopril in Pharmaceutical Formulations Using Boron-Doped Diamond Electrodes

Captopril lacks of an aromatic chromophore required for facile direct UV detection and also has two chiral centers; therefore its determination in pharmaceutical dosage forms is very challenging. Here, we developed an analytical methodology and quantified captopril in two samples of pharmaceutical formulations by square-wave voltammetry. The analytical signal response was obtained by electrochemical oxidation of the captopril drug at a boron-doped diamond electrode. The determination was carried out in 0.04 mol L-1 Britton-Robinson pH 9 buffer solution. Captopril oxidation reveals well-defined irreversible oxidation peaks. The analytical curve was obtained in the concentration range from 20 to 100 mg L-1 (r = 0.9986) with a detection limit of 36.0 μg L-1 (0.165 μmol L-1). For one sample analyzed, recovery values were in the range 96.6-98.14%, while for the other sample they were within 97.6 and 98.5%, indicating no matrix interference effects on the analytical determination for both captopril commercial samples.