Voltammetric determination of insecticide thiodicarb through its electrochemical reduction using novel solid amalgam electrode fabricated with silver nanoparticles

•Novel solid amalgam electrode fabricated with silver nanoparticles is demonstrated.•The electrode presented performance better than conventional amalgam electrode.•Thiodicarb determination was performed with amalgam electrode for the first time.•The method was successfully employed for quantification of thiodicarb in soymilk.•LOD was the lowest among all the methods for voltammetric analysis of thiodicarb.

In this work we investigated the electrochemical behavior of insecticide thiodicarb and carried out its electroanalytical determination using novel solid amalgam electrode fabricated with silver nanoparticles for the first time. Cyclic voltammetry (CV) and square-wave adsorptive stripping voltammetry (SWAdSV) were used to carry out the electrochemical and analytical studies. The best voltammetric response was achieved through the optimization of the experimental and instrumental parameters. Thiodicarb presented its optimum analytical signal in a medium composed of 0.02 mol L−1 Britton-Robinson buffer at pH 6.0. Two voltammetric peaks were observed, one oxidation peak at Ep = −0.51 V and one reduction peak at Ep = −0.64 V (vs. Ag/AgCl). The electrochemical process was characterized as an irreversible system. The cathodic signal was used for the quantitative studies performed with SWAdSV. Thiodicarb showed linear dependence over the surface of the amalgam electrode for the concentration range from 1.05 × 10−7 to 1.52 × 10−6 mol L−1 and the limit of detection achieved was 2.03 × 10−8 mol L−1. Good repeatability (RSD = 3.8%) and reproducibility (RSD = 6.1%) were found. The voltammetric method developed here allowed the determination of thiodicarb in soymilk samples at levels below those determined by European Union and Brazil with good accuracy. The results were validated using high-performance liquid chromatography and indicated satisfactory concordance. Based on the data described here, the novel silver solid amalgam electrode presented enhanced analytical performance and showed itself as promising to be used on the routine analysis of thiodicarb in food samples.

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