Conditioning of renewable silver amalgam film electrode for the characterization of clothianidin and its determination in selected samples by adsorptive square-wave voltammetry

A new square-wave adsorptive stripping voltammetric (SWAdSV) method was developed for the determination of the neonicotinoid insecticide clothianidin (Clo), based on its reduction at a renewable silver amalgam film electrode (Hg(Ag)FE). The key point of the procedure is the pretreatment of the Hg(Ag)FE by applying the appropriate conditioning potential (−1.70 V vs. Ag/AgCl reference electrode). Under the optimized voltammetric conditions, such pretreatment resulted in the peak for the Clo reduction in Britton–Robinson buffer pH 9.0 at about −0.60 V, which was used for the analytical purpose. The developed SWAdSV procedure made it possible to determine Clo in the concentration range of 6.0×10−7–7.0×10−6 mol L−1 (LOD=1.8×10−7 mol L−1, LOQ=6.0×10−7 mol L−1) and 7.0×10−6–4.0×10−5 mol L−1 (LOD=1.3×10−6 mol L−1, LOQ=4.2×10−6 mol L−1). The repeatability, precision, and the recovery of the method were determined. The effect of common interfering pesticides was also investigated. Standard addition method was successfully applied and validated for the determination of Clo in spiked Warta River water, corn seeds samples, and in corn seeds samples treated with the commercial formulation PONCHO 600 FS.