New strategy for amperometric determination of nabam pesticide by using potential assisted surface oxide regeneration method

This project demonstrates a novel amperometric method to measure the concentration of nabam through a process of potential assisted surface oxide on the copper based electrode. Based on the strong cuprous ion chelating capability of nabam, the cuprous oxide layer is dissolved away from the electrode surface. A subsequent oxidative current induced from regeneration of the oxide layer was used to reflect the concentration of the nabam. Under a set of optimal conditions with operating potential at −125 mV in the 50 mM phosphate buffer, pH 5.75, a suitable dynamic range of nabam from 0.2 μM to 10 μM (or 0.051–2.56 ppm) was achieved, which meets the requirement of the Joint FAO/WHO Meeting on Pesticide Residues. This method is free from the environmental interferences. However, most of all metal ions show a negative deviation due to the formation of other metal–nabam complexes. Here, a simple cation exchange column was used to release the chelated nabam molecule. Finally, two successful real applications were demonstrated by using a standard addition procedure after this cation exchange pretreatment.