Differential-pulse polarographic determination of the insecticide imidacloprid in commercial formulations

Abstract

The reduction reaction of imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] at a mercury electrode shows two well-defined waves in the range of pH 2.0–11.0. The characteristics of the electrode processes were examined. The analyte captures four electrons in the first step and two in the second to give the hydroxylamine and amine derivatives, respectively. A differential-pulse polarographic method for the determination of imidacloprid based on the first reduction peak of this compound is presented. Britton-Robinson buffer was used as a supporting electrolyte and optimum pH value was found to be pH 8.O. The applicable concentration range was from 10 to 200 ng/ml, with a relative standard deviation of 1.5% (for a level of 80 ng/ml) and a detection limit of 3 ng/ml. The method has been satisfactorily applied to the determination of imidacloprid in commercial formulations.