Determination of the oxygen-to-uranium ratio in uranium dioxide by differential-pulse polarography

Abstract A differential-pulse polarographic method for the determination of non-stoichiometry in uranium dioxide powders and pellets is described. The method is based on the dissolution of the sample in 2 M sulphuric acid—hydrofluoric acid under an inert atmosphere and subsequent determination of uranium(VI) by differential-pulse polarography and uranium(IV) by redox titrimetry. Uranium(VI) is reduced at a dropping mercury electrode at a peak potential of −020 vs. SCE. The measurement of uranium(VI) is done with a drop time of 1 s and a pulse amplitude of 100 mV. Reproducibilities of 0.0002 O/U ratio for UO 2 pellets and 0.002 O/U ratio for UO 2 powders were achieved.