Application of two-tracer isotope dilution mass spectrometry in the determination of uranium in geological samples

The determination of the uranium concentration in mineral samples using two tracer (²³³U and ²³⁵U) mass spectrometric isotope dilution techniques is described. The precision and accuracy are discussed and results are compared with those obtained by x-ray fluorescence and instrumental neutron activation methods. Based on the two independent values obtained for the same dilution, parameters such as the chemical procedures adopted, effect of mass fractionation and uranium distribution in minerals are evaluated. The ability of the method to distinguish between the analytical errors and heterogeneous distribution of uranium is discussed.