Abstract: An efficient separation procedure for uranium from soils by TOPO chromatographic extraction has been developed. The procedure has been optimized experimentally for the size of the column, different concentrations of nitric acid for column load, column rinse and the different types of eluant. Uranium is recovered with approximately 98.1% efficiency by the improved and optimized procedure. The decontamination factors for the soil matrix is approximately 1.4×10~3 up to 1.8×10~5.The instrumental mass bias is usually calculated from the analyses of reference materials with certified isotope abundance ratios. For both scan and jump mode the isotope discrimination correction are evaluated and the relative standard derivations(s_r) are compared. The results show good agreement for both modes. The s_r of the isotope abundance ratio~(235)U/~(238)U is better than 1% whereas those for~(234)U/~(235)U,~(236)U/~(235)U,~(234)U/~(238)U and~(236)U/~(238)U are better than 5%.