Screen-printed gold electrode for ultrasensitive voltammetric determination of the antipsychotic drug thioridazine

A highly sensitive, fast and simple analytical procedure for analysis of the antypsychotic drug thioridazine (TDZ) using an original screen-printed gold electrode (SPAuE) was developed. The cyclic voltammetry, scanning electron microscopy, electrochemical impedance and energy-dispersive X-ray spectroscopy were used for the SPAuE characterization. The results showed the advantage of the commercially available SPAuE in terms of working electrode active surface and the efficiency of kinetics of electron transfer compare to unmodified and ex situ modified gold film screen-printed carbon electrode. Moreover, the results displayed that an irreversible, adsorption-controlled oxidation process of TDZ in phosphate buffered saline of pH 2.6 is connected with the strong affinity of sulfur atoms for gold. The SPAuE allows for a much lower detection limit (2.9 x 10-12 M) than in the case of other electrochemical sensors used for TDZ analysis. The measurements results were validated by official and standard addition methods.