Electrochemical oxidation at a glassy carbon electrode of the anti-arrhythmia drug disopyramide

A voltammetric study of the oxidation of disopyramide has been carried out using a glassy carbon electrode. The electrochemical oxidation of disopyramide was investigated by cyclic, differential pulse, and square wave voltammetry. The oxidation of disopyramide is an irreversible, diffusion-controlled process. The diffusion coefficient of disopyramide was calculated in pH 7.0 phosphate buffer to be D-disopyramide = 3.8 x 10(-6) cm(2) s(-1). The oxidation of disopyramide is also pH dependent and for electrolytes with pH between 4 and 7 occurs with the transfer of one electron and one proton. In alkaline electrolytes, two consecutive charge transfer reactions are observed: both oxidation reactions involve the transfer of two electrons but only the first also involves the transfer of two protons. Two procedures for the analytical determination of disopyramide in pH 7.0 phosphate buffer were developed and compared and a detection limit LOD = 1.27 mu M was obtained.