Electroanalysis of the Anthelmintic Drug Bithionol at Edge Plane Pyrolytic Graphite Electrode

An electrochemical study of the anthelmintic drug bithionol using edge plane pyrolytic graphite electrode (EPPGE) is presented for the first time by applying different electrochemical techniques, such as cyclic voltammetry (CV), square-wave voltammetry (SWV), square-wave adsorptive stripping voltammetry (SWAdSV), and alternating current (AC) impedance spectroscopy. Mechanistic aspects of the electrode reaction were studied implying a quasireversible electrode reaction from an adsorbed state of the reactant, coupled with a follow-up chemical reaction to a final electroinactive product. The overall mechanism appears totally irreversible under conditions of CV at moderate scan rate, while being quasireversible under conditions of the fast SWV. Furthermore, an optimisation of the analytical procedure for quantitative determination of bithionol was conducted by applying SWV in an adsorptive stripping mode. The calibration curve was constructed in the concentration range of 0.1-1.0 mu mol L-1 (R-2=0.9984) with a sensitivity of 3.6 mu A L mu mol(-1) and LOD of 26.7 nmol L-1. The simple and sensitive SWAdSV procedure was proved to be suitable for the analysis of spiked urine samples.