Electrochemical determination of lacidipine

Lacidipine is an antihypertensive drug that is oxidizable at the glassy car bon electrode. The voltammetric oxidation of lacidipine in aqueous-alcoholi c solutions (70 + 30) produces a well-defined voltammetric peak when subjec ted to a differential pulse voltammetric experiment. This peak is due to ox idation of the dihydropyridine ring to a pyridine derivative. This voltamme tric response result is irreversible, pH dependent, and diffusion controlle d. The best resolution for the peak was obtained at pH 6 in Britton-Robinso n buffer-ethanol (70 + 30), The peak potential at pH 6 was 800 mV against a n Ag-AgCl reference electrode. A linear relationship between peak current a nd lacidipine concentration was obtained. For analytical purposes, a calibr ation curve for lacidipine that covered concentrations between 5 x 10(-6) a nd 2 x 10(-4) M was used. Detection and quantitation limits were 3.52 x 10( -6) and 3.78 x 10(-6)M, respectively. The repeatability of the measurement was 2%. On the basis of the voltammetric response, we also developed high-p erformance liquid chromatographic methods with electrochemical detection. F or comparative purposes, we also developed a spectrophotometric method.