Abstract

Cadmium concentration in an aqueous medium is quantified using an alginic acid-modified carbon paste electrode. The working electrode was prepared using a homogeneous mixture of graphite powder, alginic acid (AA) and mineral oil. Square wave anodic stripping voltammetry (SWASV) using this modified electrode showed one small well-resolved anodic wave for the oxidation of AA at -0.05 V. This signal shifts toward less positive potential and peak current increases in the presence of Cd(II). After optimizing the experimental conditions, the anodic peak current of Cd(II)-AA was linearly related to its concentration up to ca. 30.0 mu g L(-1), with a detection limit of 0.9 mu g L(-1) at pH 2.0 (HNO(3). t(acc) = 60 s, E(acc) = -0.80 V). The method was validated by determining Cd(II) in spiked synthetic sea water (ASTM D665). The modified electrode showed good stability and repeatability.