Determination of thallium in aqua regia soil extracts by ICP-MS

In our study the method for the determination of Tl by ICP-MS was optimized . Both isotopes, Tl-203 and Tl-205, were used for the measurement. Lutetium at a concentration 0.4 mg L-1 was used as an internal standard. Soil extra cts were measured after dilution (1+4 with the solution of lutetium 0.5 mg L-1). Several soils from the International Soil Exchange Programme (WEPAL) were analyzed for the comparison of the results. For all tested samples the achieved results were in a good agreement with the results reported by WEP AL. A detection limit 1.2 mu g kg(-1) was achieved for the samples. The met hod was used for the determination of thallium in soils collected in the na tional monitoring programme (200 sites) and in the monitoring programme of the contaminated areas (27 sites). Topsoil and subsoil were sampled on each site and analyzed separately (454 samples were analyzed). The median value for the tested soils was 0.25 mg/kg, lower and upper quartiles 0.19 and 0. 32 mg kg(-1) respectively, 10(th) and 90(th) percentiles 0.16 and 0.41 mg k g(-1) respectively and the maximum value was 2.83 mg kg(-1).