Stripping voltammetric determination of cadmium in sea water using a carbon paste electrode modified with alginic acid from brown algae

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 CdII. After optimizing the experimental conditions, the anodic peak current of CdII-AA was linearly related to its concentration up to ca. 30.0 µg L-1, with a detection limit of 0.9 µg L-1 at pH 2.0 (HNO3. t acc = 60 s, Eacc = -0.80 V). The method was validated by determining CdII in spiked synthetic sea water (ASTM D665). The modified electrode showed good stability and repeatability.