Deaeration method for imidacloprid determination on glassy carbon electrode.

Abstract

In this work deaeration methods were investigated for chronopotentiometric determination of pesticide imidacloprid [1-(6-chloro-3-pyridyimethyl)-N-nitroimidazolidin-2-ylideneamine] on glassy carbon electrode. As a supporting electrolyte, a Britton-Robinson buffer was used. All investigations were carried out in model systems. Cathodic peak of imidacloprid could not be registered only in BrittonRobinson buffer, due to electrochemical reduction of dissolved oxygen. For this reason, it was necessary to investigate different deaeration methods for removing oxygen from the solution. Within this, deaerations by various reductants and by passing a nitrogen stream were compared. Investigated reductants were sodium sulfite, ascorbic acid, oxalic acid, potassium bromide and sodium bromide. Combinations of a certain reductant and nitrogen were compared as well. Addition of a saturated solution of sodium sulfite directly in the tested solution proved as the best deaeration method. This method provided fast deaeration step as it took less than a minute for completely removing the oxygen. An optimal concentration of the solution of sodium sulfite was also investigated. Concentrations of sodium sulfite were tested in the range of 0.6 g/idm* to 230 gidm?. Considering the height of the analytical signal and its reproducibility, concentration of 8.8 gldm? showed as optimal. This method could be applied for the determination of imidacloprid in commercial formulations and some real samples.