The affinity of two widely used pesticides of diverse specificities, i.e., the fungicide Thiram and the herbicide Picloram, for lead ions has been studied by an electrochemical approach. The anodic stripping voltammetric profile of the studied metallic ion was significantly affected by the chemical nature of pesticide (ligand) used and new light has been shed on the nature, strength and possible stoichiometry of formed complexes. Thiram caused a pronounced effect on the stripping signals of Pb. Linearization algorithms of titration data with the metal allowed the conditional stability constant to be calculated for Thiram (log K' = 6.8) and Picloram (log K' = 6.0). It was found that both pesticides contribute to the formation of the respective 1:1 complexes with Pb in a high percentage (ca. 83%).
Thiram; Picloram; pesticides; lead; complexation
