Problems of selenium fractionation in soils rich in organic matter Original Research Article

Hydride generation atomic absorption spectrometry (HGAAS) was used for the determination of Se in soils. Potential interferences from metal ions and spectral interference in the heated quartz tube were documented and eliminated. The efficiency of four acid-based closed vessel decomposition procedures was checked with certified reference soils and a pressured microwave sample preparation using (1 + 1) HNO3 : H2SO4 was recommended for the determination of total Se components in soils. The effect of a high content of organic matter on the reliable determination of Se was examined and eliminated. A sequential extraction procedure was developed for the determination of the speciation of Se in a forest soil profile. The detection limit for the total Se determination was 6 ng Se/g soil, and the relative standard deviations were <5% after application of the sequential extraction procedure. The proposed method was applied to a real forest soil sample and the vertical distribution of Se species in the soil profile was investigated and evaluated.