Electroanalytical detection of Pb, Cd and traces of Cr at micro/nano-structured bismuth film electrodes

A micro/nanoparticle (μ-NP) bismuth film electrode (BiFE) has been developed for the determination of lead and cadmium by anodic stripping voltammetry (ASV) and trace levels of chromium by adsorptive stripping voltammetry (AdSV). Chromium was detected in a flow cell. Bismuth was electrodeposited on a hydrated aluminum oxide template, which was previously coated on a glassy-carbon (GC) electrode. Then, the template was selectively removed by soaking the electrode in a 0.1 M NaOH solution for 30 min, leaving a dispersed bismuth film covering the electrode surface; such electrodeposits had a particulate appearance, which was observed by scanning electron microscopy (SEM). The voltammetric analyses from a chromium solution on a μ-NPs/BiFE provided a limit of detection (LOD) equal to 0.12 ng L⁻¹ (n = 6) and a slope of 0.27 μC/ng L⁻¹ (R² = 0.9903). The signals registered were more than 50 times higher than the peaks obtained from a conventional BiFE. The analysis of aqueous solutions of Cd and Pb gave also lower LOD and higher sensitivity against the conventional BiFe experiments.