DETERMINATION OF TRACE-ELEMENTS IN CALCITE BY ICP-AES AFTER COPRECIPITATION WITH INDIUM SULFIDE

The separation and determination of trace elements in calcite by ICP-A ES were examined. Trace elements (Al, Bi, Cd, Co, Cr, Cu, Fe, La, Mn, P, Sn, Sb, Ti, V, Y, Zn and Zr) in calcite were separated from calcium by the following procedure: calcite (0.3 g) was resolved by hydrofluo ric, nitric and perchloric acids. The resolved solution was diluted by water (200 ml), and adjusted to pH 1. Carrier indium (30 mg) was then added to the solution. The pH of the solution was adjusted to 9 with diluted aqueous ammonia (300 ml); thioacetamide (0.1 g), which makes t he sulfide ion, was then added to this solution. Trace elements were t hen coprecipitated with the indium sulfide. This precipitate was resol ved by aqua regia, and the trace elements were analyzed by ICP-AES. Th e coprecipitation ratio of the trace elements was 89-100%. The present method was efficient for the determination of elements (Cd, Co, Cu, M n and Zn) that form complexes with ammonia. The analytical values of t race elements in calcite agreed with those determined by other methods . However, the determination of cobalt, antimony, titanium and lanthan um was interrupted by a large amount of iron in sediment samples.