Sequential separation and determination of uranium and thorium isotopes in soil samples with Microthene-TOPO chromatographic column and alpha-spectrometry

Abstract

In the method, soil was fused together with Na2CO3 and Na2O2 at 600 °C, uranium and thorium were leached out with HCl, HNO3 and HF, and HClO4 was used to eliminate the residual HF through evaporation. The leaching solution (2 M HNO3) was passed through a Microthene-TOPO column to adsorb uranium and thorium. Thorium was first eluted with 2 M HCl and electrodeposited in 0.025 M H2C2O4 + 0.15 M HNO3 on a stainless steel disc. Uranium was eluted with a 0.025 M ammonium oxalate solution and also electrodeposited. Both thorium and uranium isotopes on the discs were measured separately by α-spectrometry.