Enhancing fouling resistance of graphite sheets for electrochemical sensing of bisphenol-A

Bisphenol A (BPA) is widely used in the production of polycarbonate plastics and epoxy resins, and it is now classified as an emerging pollutant due to its extensive environmental presence. Given the need for effective BPA monitoring, this study presents a cost-effective electrochemical approach for its quantification, using pyrolytic graphite sheets (GSs) as working electrodes integrated into a 3D-printed electrochemical cell. Despite initially exhibiting an intense voltammetric peak for BPA, fouling of the GS surface resulted in a progressive decrease in the BPA signal over successive scans. A pretreatment consisting of applying +1.5 V for 30 s under continuous stirring was adopted before voltammetric measurements. This pretreatment promotes the oxygen evolution reaction, likely cleaning the electrode surface and enhancing its antifouling capability by introducing oxygenated functional groups onto the GS surface. In contrast, this pretreatment was ineffective for a glassy carbon electrode (GCE), likely due to its morphology and reduced reactive surface area, which inhibited the formation of oxygenated functional groups. Under optimized conditions, differential pulse voltammetry with the treated GS electrode yielded a linear range for BPA detection from 0.5 to 1.9 μmol L^-1, achieving a detection limit of 0.12 μmol L^-1. The proposed electrochemical method was applied to quantify BPA in drinking water and vacuum-pressure mouthguard sheets, providing results statistically equivalent to those obtained using high-performance liquid chromatography. Therefore, this paper presents interesting findings that we believe to be significant for the electroanalysis community, particularly in developing countries where research funding is often limited.