In this presentation, a procedure for the determination of ng/g levels of technetium-99 in uranium dioxide powder, hydrolyzed uranium hexafluoride (Hex), and uranyl nitrate liquor (UNL) is discussed, and three methods for the dissolution of uranium dioxide are compared. Digestion of uranium dioxide using concentrated nitric acid in a stoppered glass tube gives variable results. A concentrated hydrochloric acid dissolution using microwave digestion in sealed TFE-fluorocarbon PFA digestion vessels gives reproducible results, as does the digestion using dilute nitric acid in open beakers. The effects of the isobaric interference of ruthenium-99 and the molecular interference of 98MoH and the use of suitable algorithms to correct for such interferences are discussed. Compensation of signal suppression due to the uranium matrix is made by the use of matrix-matched calibration standard solutions and instrumental drift is monitored and corrected by the addition of rhodium as an internal standard. A detection limit (2 s) of 0.3 ng g−1 U is achieved using a solution containing 2 g of uranium per litre and a 30-s per isotope acquisition time, using “peak jump” mode.