Effect of Surface-Active Compounds on the Stripping Voltammetric Response of Bismuth Film Electrodes

The influence of model surface-active macromolecules on the stripping voltammetric response of bismuth film electrodes was evaluated. Gelatin, albumin, humic acid, and Triton X-100 were used as representative surfactants, while lead and cadmium were employed as test metal ions. The adsorption of these surfactants onto the bismuth electrode caused a gradual decrease of the stripping peaks. The faster and larger suppressions observed at the bismuth electrode (compared to the mercury one) in the presence of albumin and Triton X-100 reflect differences in the adsorption kinetics and equilibrium of these surfactants at these electrodes. The surfactant interference at bismuth stripping electrodes can be circumvented using a permselective/protective Nafion coating. The effective resistance to surfactant effects makes the Nafion-coated bismuth electrode very attractive for practical stripping applications. A Nafion-modified stripping electrode is applied for measurements at large sample-instrument distances.