Uncertainty Evaluation for Determination of Total Uranium in Primary Reference Material U₃O₈ by Potentiometric Titration

The determination of total uranium in primary reference material U₃O₈ by potentiometric titration method was discussed. A mathematical model of measurement component was established to compare the uncertainty factors during measurement process. It was found that the uncertainty of quantity of samples has maximal contribution, the uncertainties of measurement repeatability and quantity of consumed potassium dichromate are in the second place, and the effect of K₂Cr₂O₇ relative molecular mass and U relative atomic mass to the final uncertainty factors is minimum. The results show that, when potentiometric titration method is used to determine total uranium in U₃O₈, an expanded uncertainty of 0.022%(k=2) is recorded at total uranium of 84.795%.