A new sensor based on ZnO nanosheets and reduced graphene oxide to electrochemical determination of thiram fungicide

Thiram is a pesticide derived from sulfur that has a highly toxic and biologically active chemical molecule due to its ability to chelate polyvalent cations, being the second most used fungicide in agriculture. Due to its toxic effects, which include liver damage, neurotoxicity, infertility problems and bone and cartilaginous malformations, among others, the detection of this contaminant in water is essential. This research work describes the development of a new glassy carbon electrode modified with electrochemically reduced graphene oxide and zinc oxide nanosheets (GCE-ErGO-ZnO) to detect the presence of the pesticide thiram by electrochemical means. The GCE-ErGO-ZnO electrode was examined morphologically and chemically and analyzed by cyclic voltammetry in the presence of thiram. Electrochemical characterization demonstrated that GCE-ErGO-ZnO presents the highest electrocatalytic activity for thiram oxidation using ZnO nanosheets. Thiram was successfully identified by the square wave voltammetry method in Britton-Robinson buffer 0.1 mol·L⁻¹, at pH = 5.0. The developed electrochemical sensor allows the quantification of thiram in the linear range 0.09–0.96 μg·mL⁻¹, with a LOD of 1.3 ng·mL⁻¹ and LOQ of 4.3 ng·mL⁻¹, significantly lower than the maximum Brazilian and global concentration levels, demonstrating that this method has significant potential to be used in monitoring this pesticide in watercourses.