Simultaneous voltammetric detection of Fe3+, Cu2+, Zn2+, Pb2+ e Cd2+ in fuel ethanol using anodic stripping voltammetry and boron-doped diamond electrodes

Abstract

The presence of metallic species in biofuels has increased considerably during the last few years. The deposition of these species in non-metallic components of automotive engines can cause their degradation due to oxidative or catalytic processes, thus decreasing their useful life. Therefore, the problem imposes the need to implement methodologies with selectivity, sensitivity and adequate reproducibility in the detection of these inorganic species. This is the first study to determine the species Fe3+, Cu2+, Zn2+, Pb2+ and Cd2+ using boron-doped diamond (BDD) electrodes in an ethanolic medium with anodic stripping voltammetry (ASV). Thus, the ASV methodological parameters for accumulation time (Tacc), accumulation potential (Eacc), frequency (f) and amplitude (a) were optimized in different electrolyte media using BDD electrodes with a doping level of 8000 ppm in the determination of these metallic species. The limits of detection (LoD) and quantification (LoQ) were obtained from the analytical curves, reaching values (LoD) below 2 µg.L−1 for all species. After the optimization of the ASV parameters, tests were performed on samples collected from different gas stations in the municipality of Manaus, Brazil.