Determination of trace amounts of beryllium by adsorptive square-wave stripping voltammetry in the presence of Thorin I

This article reports on the use of adsorptive stripping voltammetry (AdSV) for the determination of beryllium on an in-situ plated mercury film electrode (HgFE). The selective chelating reagent used was 1-(o-arsonophenylazo)2-naphthol-36-disulphonic acid (Thorin I), which forms a stable complex with beryllium. Thorin I exhibits adsorptive activity toward beryllium, and the resulting "reagent-analyte" complex provides a reduction peak during cathodic potential scanning. Various factors affecting the magnitude of a stripping signal were studied, optimal conditions for mercury film deposition were selected, and a potential-time program was developed for the stages of the inversion cycle. As a result of the research conducted, optimal analytical conditions for measuring the analytical signal were established: 0.1 mol center dot L-1 ammonium buffer (pH = 9.5) containing 1 x 10-6 mol center dot L-1 Thorin I and 7.5 x 10-4 mol center dot L-1 mercury (II), with subsequent square-wave scanning mode. The calibration curve was linear in the beryllium concentration range from 0.6 to 7.7 mu g center dot L-1, with a detection limit at an accumulation time of 90 s of 0.08 mu g center dot L-1. The interference effects of 10 foreign ions were studied, and a way to eliminate some of them was found. The use of in-situ HgFE eliminates the need for a large amount of mercury compared to previously used stationary mercury electrodes and ensures high reproducibility of the response of a 0.9 mu g center dot L-1 beryllium solution (n = 10; RSD = 3.6%) without the need for repeated mercury film application. The result of the work is a technique that was successfully applied for the determination of beryllium in natural water, beryl mineral, and beryllium-containing concentrate. The results were compared with measurements performed by an external analysis laboratory via ICP-OES.