Bulk determination of uranium and thorium in presence of each other by Total Reflection X-ray Fluorescence spectrometry

A study to assess the applicability of Total Reflection X-ray Fluorescence (TXRF) spectrometry as a microanalytical technique for the determination of uranium and thorium as major elements in presence of each other has been made. Effect of dilution of the sample on the analytical results has been investigated. It has been found that dilution of the sample does not affect the analytical results significantly. Also the analytical results of uranium and thorium are similar with different internal standards e.g. cobalt, gallium and yttrium. With a sample size of 10 μL and the concentrations of the analytes in the range of 1–50 μg/mL and total matrix concentration less than 200 μg/mL, the precision and accuracy of the method were found to be better than 3% (1 s) and 4%, respectively. For higher concentration ranges of the analyte (up to about 700 μg/mL), the precision and accuracy values were better than 6% (1 s) and 5%, respectively. The TXRF method has an advantage of using small sample volume of about 10 μL, produces very small radioactive waste and is nondestructive but requires dissolution of the sample.