Processes during anodic stripping voltammetry determination of lead in the presence of copper on a solid electrode modified with 2,2′-bipyridyl in polyaniline

Investigations of the processes during the determination of lead in the presence of copper by anodic stripping voltammetry (ASV) on solid electrodes modified with 2,2'-bipyridyl in a polyaniline matrix were carried out. During the preconcentration step a metal solid solution layer is deposited on the cathode. Interactions between lead and copper atoms in the solid solution change the potentials and currents of the peaks corresponding to anodic stripping. These changes cause serious errors in quantitative determination of the metals. 2,2'-Bipyridyl forms a stable complex with copper ions and the accuracy of lead determination is significantly improved. The molecules of 2,2'-bipyridyl were immobilized on the electrode surface in a polyaniline film obtained during electrochemical oxidation from the solution containing aniline, the ligand, and sulfuric acid. ASV measurements were carried out in acetate buffer (pH = 4.5). Complementary data were obtained in spectrophotometric UV-VIS measurements of lead and copper complexes in acetate buffer and by the analysis of atomic force microscopy images of the modified glassy carbon electrode. Quartz crystal microbalance results were used to propose the mechanism of the processes occurring at the modified electrode surface. (C) 2001 Elsevier Science B.V. All rights reserved.