ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of Selenium in Soils by Cathodic Stripping Voltammetry after Separation as Gaseous Selenium Tetrabromide

D. Rúriková and I. Kunáková

Department of Analytical Chemistry, Faculty of Natural Sciences, Comenius University, SK-842 15 Bratislava

Abstract: A procedure for soils has been developed that uses a nitric/sulfuric acids digestion to solubilize total selenium and a distillation treatment to release selenite and selenate in the form of gaseous SeBr4. The advantage of distillation treatment procedure is that analyte is separated from the interfering matrix and simultaneously converted to electroactive form Se(IV). Optimum procedures for decomposition of the soil samples and for separation of low contents of Se from the interfering components were investigated. This procedure was used for determination of extractable forms of Se as well. The selenium(IV) was determined by differential pulse cathodic stripping voltammetry (DPCSV) with hanging mercury drop electrode in the presence of added copper(II). Concentration of Se was evaluated by the method of standard additions on the basis of the signal arising on reduction of Cu(I) in the deposited copper(I) selenide. The developed procedure is simple as to the number of operations preceding the determination itself and reliable for determination of very low contents of Se in various types of soils and soil extracts as evidenced by low values of relative standard deviations (0.8-4.9 %). The detection limit for total selenium is w = 5 x 10^-9 using a sample size of 0.3 g.

Full paper in Portable Document Format: 534a246.pdf

Chemical Papers 53 (4) 246–251 (1999)