Voltammetric Determination of Prochlorperazine and Ethopropazine Using a Gold Electrode Modified with Decanethiol SAM

The voltammetric behavior of prochlorperazine and ethopropazine at a decanethiol (DEC) self-assembled monolayer (SAM) modified gold electrode (DEC/Au) has been studied. It was observed that prochlorperazine exhibited an anodic peak at about 0.60 V (vs SCE), while ethopropazine exhibited two anodic peaks at about 0.49 V and 0.58 V on DEC/Au in pH 10 sodium carbonate buffer. This was due to their different electrochemical oxidation mechanisms. In this case, the oxidation of prochlorperazine and ethopropazine included one 2e step and two 1e steps, respectively. In the presence of some reductants such as ascorbic acid, the oxidation products of them can catalyze the oxidation of the reductants and thus make the peaks grow. In addition, it was found that the SAM structure became not so compact when prochlorperazine and ethopropazine were present, resulting from their permeating in the SAM. Various conditions were optimized for their determination. Under the selected conditions (i.e. 0.080 M pH 10 sodium carbonate buffer; scan rate: 100 mV/s; accumulation potential: –0.4 V or 0 V; accumulation time: 60 s), the peak currents were linear to prochlorperazine concentration in the ranges of 0.1~2.0 M and 5.0~50 M, and linear with ethopropazine in the ranges of 10 nM~0.1 M and 0.5~20 M. The RSD was 4.28% for 8 successive measurements of 1.0 M prochlorperazine. The influence of some coexistents was examined.