Electrochemical Oxidation of Chlorpromazine Hydrochloride in Aqueous Buffer

Abstract

The electrochemical oxidation mechanism of chlorpromazine hydrochloride (CPZ-HCI) was examined in aqueous buffers in the pH range from 2 to 7. Three anodic waves were observed on the cyclic voltammogram of CPZ. The peak potential of the second wave was highly dependent on the properties of the supporting electrolyte, but the first peak was independent of these properties. At a higher pH or higher concentration of electrolyte, both peak currents increased. The final oxidation product was found to be chlorpromazine sulfoxide by comparison of its ultraviolet (UV) absorption spectrum and Rf value of thin layer chromatography (TLC) with those of an authentic sample. The experimental results suggest that the first wave is a catalytic wave and depends on the pH and the concentration of the supporting electrolyte, but that the second is an oxidation wave of CPZ-buffer anion adducts.