Voltammetric detection of silver(I) using a carbon paste electrode modified with keratin

Abstract

The voltammetric detection of silver(I) was carried out at a carbon paste electrode (CPE) modified with keratin. Silver(I) was selectively accumulated on the electrode on the basis of its interaction with the thiol and disulfide groups of keratin in 0.1 mol dm^–3 acetate buffer (pH 6.7) + 0.1 mol dm^–3 NaClO₄. After reduction of silver(I) had been carried out, the reoxidation wave of silver(0) appeared at 0.14 V (versus Ag/AgCl) on scanning the potential in the positive direction in 0.1 mol dm^–3 acetate buffer (pH 6.7). The detection limit of silver(I) was 2 × 10^–8 mol dm^–3 when the accumulation time was 10 min. Interference from co-existing substances was slight in the voltammetric measurement because of the interaction with sulfur atoms and the exchange of the medium. The proposed method was applied to the determination of silver(I) in a photographic developer.