The need to measure the concentration of Se in food, environmental objects etc is well-known. The stripping voltammetry is one of the commonly used methods for that. In some processes Se is accumulated in the form of a hardly soluble compounds in the presence of a suitable metal ions, normally copper. Cu~(2+) + 2e +Hg → Cu~0(Hg) (1) SeO_3~(2-) + xCu(Hg) + 6H~+ + 4e → Cu_xSe(Hg) + 3H_2O (2) The electrochemical reduction of the precipitate thus obtained results in the formation of the charachteristic peak on the voltammogram, its height being proportional to the concentration of Se in the solution: Cu_xSe(Hg) + 2H~+ + 2e → H_2Se + xCu(Hg). (3) Good sensitivity and reproducibility were found for the case of the mercury drop electrode only so far. The use of the mercury film electrode results in the considerably worse metrological characteristics of the analysis (Lange and Scholz 1997). The present work aims at the development of the method of Se (Ⅳ) determination by stripping voltammetry on the the mercury drop electrode, pre-doped with Cu, which was not done so far.
展开▼
