Application of Catalytic Hydrogen Evolution in the Presence of Neonicotinoid Insecticide Clothianidin

Clothianidin, a new generation of pesticide, was determined in spiked tap water, apple juice, and soil by square-wave adsorptive stripping voltammetry. The method of determination is based on the hydrogen evolution reaction catalyzed by clothianidin at the hanging mercury drop electrode. The optimal signal was detected at -1.4 V versus Ag/AgCl in citrate buffer at pH 2.2. Various parameters such as pH, buffer concentration, frequency, amplitude, step potential, accumulation time, and potential were investigated to enhance the sensitivity of the determination. The optimal results were recorded at an accumulation potential of -0.35 V, accumulation time of 7 s, amplitude of 100 mV, frequency of 200 Hz, and step potential of 7 mV. The mechanism of catalytic hydrogen evolution was considered under experimental and theoretical conditions. This electroanalytical procedure enabled to determine clothianidin in the concentration range 9 x 10(-9)-4 x 10(-6) mol L-1 in supporting electrolyte and tap water, 1 x 10(-7)-4 x 10(-6) mol L-1 in diluted apple juice, and 2 x 10(-7)-1 x 10(-6) mol L-1 in soil. The detection and quantification limits in supporting electrolyte and diluted apple juice were found to be 2.6 x 10(-9), 8.6 x 10(-9) and 3 x 10(-8), and 1 x 10(-7) mol L-1, respectively. A standard addition method was successfully used to determine clothianidin in spiked tap water, spiked apple juice, and spiked soil.