DETERMINATION OF TOTAL SELENIUM CONTENT IN SEDIMENTS AND NATURAL-WATER BY GRAPHITE FURNACE-ATOMIC ABSORPTION-SPECTROSCOPY AFTER COLLECTION AS A SELENIUM(IV) COMPLEX ON ACTIVATED CARBON

A trace level of Se was collected on activated carbon (AC) as the Se(IV)-3-phenyl-5-mercapto-1,3,4-thiadiazole-2(3H)-thione (Bismuthiol II) complex. The AC was directly introduced as an AC-suspension into the graphite tube atomizer and the Se concentration was determined by atomic absorption spectroscopy (T. Okutani, T. Kubota, N. Sugiyama and Y. Turuta, Nippon Kagaku Kaishi, (1991) 375). The amount of Se in heavily contaminated samples including sediment, lake water and seawater was determined using this method. The sediments were digested with HNO3-HClO4-HF and the interference from AlF3 was removed using H3BO3-HClO4. Lake water and seawater were acidified with H2SO4 and digested with KMnO4. The Se concentrations of these samples were determined by this method with satisfactory results. The above method is simple, rapid and applicable to heavily contaminated samples.