An innovative method for determination of uranium isotopes in soils by alpha-spectrometry coupled with Microthene-TOPO column separation

In the new procedure for determination of uranium isotopes by alpha-spectrometry, silica in the leachate of fused soil samples was coated with polyethylene glycol 2000 and eliminated through filtration, and uranium isotopes were separated from other alpha-emitters with a Microthene-TOPO column and electrodeposited on a stainless steel disc for measurement. It was observed that treatment with HF has negligible contribution on the release of uranium from the leachate containing silicates, so the use of HF for mineralization can be avoided. The reference material IAEA-315 marine sediment was analysed, and the obtained U-238, U-234 and U-235 concentrations are in good agreement with the certified values. The detection limit for soil samples was 0.23 Bq kg(-1) for U-238 or U-234 and 0.08 Bq kg(-1) for U-235 if 0.5 g of samples were analysed. Method application shows that (1) the yields are high and stable, and (2) no interference from other alpha-emitters are observable in the final spectra.