Polymer-coated bismuth film electrodes for the determination of trace metals by sequential-injection analysis/anodic stripping voltammetry

In this work, the utility of polymer-coated bismuth film electrodes (BiFEs) was assessed for the simultaneous on-line determination of Cd(II), Pb(II) and Zn(II) by square-wave anodic stripping voltammetry (SWASV) in the sequential-injection analysis (SIA) mode. The polymeric Nafion coating was initially plated on a glassy carbon electrode forming part of the flow-through electrochemical cell. The subsequent steps of the bismuth layer generation, analyte preconcentration, voltammetric measurement and electrode cleaning were conducted on-line. For a sample volume of 1.2 mL, the limits of detection (at S/N = 3) were 2 μg L−1 for Cd(II) and Pb(II) and 6 μg L−1 for Zn(II), the coefficients of variation at 20 μg L−1 were 5.1% for Cd(II), 5.9% for Pb(II) and 6.2% for Zn(II) and the measurement frequency was between 10 and 20 h−1 (depending on the sample volume aspirated). It is demonstrated that the polymer-coated BiFEs, combined with SIA, can provide an environmentally friendly, sensitive and robust tool to perform rapid and cost-efficient on-line monitoring of trace metals by ASV, even in the presence of surface-active compounds.