Electrooxidation of pimozide and its differential pulse voltammetric and HPLC–EC determination Original Research Article

The oxidative behaviour of pimozide was studied in hydroalcoholic media (10+90 methanol–H2O, pH range 2–7.5) at carbon based electrodes. Pimozide was irreversibly oxidized at high positive potentials, resulting in the formation of a couple with a reduction and re-oxidation peak at much lower potentials. The response was evaluated with respect to pH, scan rate, addition of surfactant and other variables. Using differential pulse voltammetry (DPV), the drug yielded a well-defined voltammetric response in Britton–Robinson buffer, pH 2.1 at +1.1 V (versus Ag/AgCl) on glassy carbon electrode. The process could be used to determine pimozide concentrations in the range 8×10−7–1×10−4 M. Applicability to tablets and human serum analysis was illustrated. Furthermore, a high-performance liquid chromatographic method with electrochemical detection (HPLC–EC) was developed, which allowed pimozide to be detected down to a level of 2.7×10−10 M (0.25 ppb).