Signal splitting in the stripping analysis of heavy metals using bismuth film electrodes:: Influence of concentration range and deposition parameters

The stripping signals of Pb(II), Cd(II) and Zn(II) in a bismuth film electrode (BiFE) ex situ plated on glassy carbon support were studied by differential pulse anodic stripping voltammetry and constant-current stripping chronopotentiometry. Regular signals were measured for Pb(II), with a good linearity inside a wide concentration range. In contrast, Cd(II) and Zn(II) produce two overlapping signals, one predominating at low metal concentrations and the other at high metal concentrations. For the detailed study of such peak splitting, multivariate curve resolution by alternating least squares has been used concluding that the total area becomes linear with metal concentration in both situations. The reasons of the peak splitting seem to be related to the accumulation of the reduced metal on BiFE in different ways. Even with that complication, the fact that the linear relationship total area versus concentration is hold reinforces the applicability of BiFE for the determination of total concentrations of metal ions inside a wider concentration range than that initially expected. However, the coexistence of signals at different characteristic potentials anticipates important difficulties in the analysis of potential shifts caused by heavy metal complexation. (C) 2008 Elsevier Ltd. All rights reserved.