Determination of Trace Amount of Bismuth(III) by Adsorptive Stripping Voltammetry by Alizarine Red S

Abstract

Controlled adsorptive accumulation of bismuth (III) complexed with alizarine red S (ARS) on a hanging mercury drop electrode provides the basis for the direct stripping measurement of this element in the nanomolar concentration level. The reduction current of adsorbed complex ions of bismuth is measured by differential pulse cathodic stripping voltammetry, preceded by an accumulation period of one minute. The peak potential is at 0.05 V (vs. Ag/AgCl). Optimal experimental parameters were found to be an ARS concentration of 15 μM, an accumulation potential of −0.2 V, and an acid concentration of 0.10 M (nitric acid). The limit of detection (3σ) is 0.5 nM, and the response is linear up to 150 nM. Many common anions and cations do not interfere in the determination of bismuth. An intercomparison of bismuth determinations performed by the proposed method and previously electroanalytical methods demonstrates higher selectivity, and shorter analysis time of this method. The voltammetric procedure was then applied successfully to the determination of bismuth in various complex samples.