ELECTROCHEMICAL BEHAVIOR OF THE ANTINEOPLASTIC AGENT ETOPOSIDE AT A GRAPHENE-BASED MODIFIED ELECTRODE: ITS SQUARE-WAVE ADSORPTIVE STRIPPING VOLTAMMETRIC DETERMINATION IN THE PHARMACEUTICAL FORMULATIONS

An electrochemical sensor based on the graphene (GR) was prepared, and used for the determination of etoposide (ETO). The electrochemical behaviors of this compound on GR modified glassy carbon electrode (GR/GCE) were investigated by cyclic voltammetry and square-wave adsorptive stripping voltammetry (SWAdSV). Using SWAdSV, a linear calibration curve was obtained for ETO determination in 0.1 M Britton-Robinson (BR, pH 4.0) buffer solution at +0.56 V (vs. Ag/AgCl) (after 30 s accumulation at 0.1 V). A linear relationship was found between peak currents and the concentration of ETO within 0.025 to 0.5 mu g mL(-1), with a detection limit of 0.0023 mu g mL(-1). The developed method was successfully applied to the determination of ETO in the pharmaceutical formulations with good recoveries.