Square wave anodic stripping voltammetry determination of eco-toxic metals in samples of biological and environmental importance

Abstract

Square wave anodic stripping voltammetry was used in simultaneous determinations of eco-toxic metals (Pb, Cd, Cu and Zn) on bismuth film electrodes. The electrodes were prepared in situ on a glassy-carbon electrode (GCE) from 0.1 M acetate buffer (pH 4.5) containing 200 μg L⁻¹ of bismuth (III), as well ex situ on electrochemically oxidized graphitized polyacrylonitrile carbon fibres from 200 mg L⁻¹ Bi(NO₃)₃ in 1% HNO₃ (aqueous) solution. Preparation of a Bi-modified carbon fibre electrode (CFE) was by cation exchange of Bi⁺³ ions for H⁺ of the acidic surface groups of the electro-oxidized carbon fibres, followed by electrochemical reduction to Bi⁰. For the Bi-GCE the linear range was 20–280 μg L⁻¹ for zinc, 10–100 μg L⁻¹ for lead, 10–80 μg L⁻¹ for copper, and 5–50 μg L⁻¹ for cadmium. For the Bi-CFE it was 20–160 μg L⁻¹ for zinc, 10–100 μg L⁻¹ for lead, 10–100 μg L⁻¹ for copper, and 2–120 μg L⁻¹ for cadmium. For both kinds of bismuth modified carbon electrodes, low limits of detection and satisfactory precision were achieved. The method was successfully applied to certified reference materials of biological (bovine liver) and environmental (mussel tissue) importance.