Attractive applications of less noble metal ions in stripping voltammetry at metal film electrodes

Abstract

An overview is dished up to show how the presence of a less noble metal ion in the samples subjected to electroanalytical measurements may sometimes lead to a positive effect on determinations of some analytes at the trace concentration level. First, an unexpected behaviour of Sb-based electrodes is mentioned allowing one its application also in the anodic potential range. A role of less noble metals is documented on the stripping voltammetric determination of mercury(II) or bismuth(III) at antimony film-coated carbon paste electrodes, where an apparent catalytic effect caused by the presence of cadmium(II) was observed offering a significant improvement of the analytical signal for both the cations. This phenomenon was attributed to the formation of intermetallic compounds during the electrolytic accumulation at the electrode surface. Very recently, a new approach was reported based on the preparation of metal film electrodes that utilize the combination of ex situ and/or in situ plating methods and the use of reversibly deposited mediator. By plating the metal film onto the surface of glassy carbon electrode together with zinc acting as mediator metal, followed by its subsequent oxidation and further deposition of the metal of interest, a higher surface coverage of the electrode with metal particles could be achieved. Application of the newly developed technique was demonstrated on the determination of nickel(II) at a lead film electrode with the aid of adsorptive stripping voltammetry, as well as on the determination of tin(IV) at a bismuth film electrode when using square-wave anodic stripping voltammetry.