Analysis of isobaric interferences in the analysis of Tc-99 with SF-ICPMS

Tc-99 is, due to its long half-life and high mobility in the environment, a fission product of concern for the safe management of nuclear waste. SF-ICPMS constitutes a powerful tool for the analysis of Tc-99 in samples from nuclear decommissioning activities or experiments on the geochemical behavior of Tc. Isobaric background in the determination of Tc-99 with SF-ICPMS arise from the molecular species Mo-98H and from the stable nuclide Ru-99. Chemical separation of Tc from Mo and Ru is effective in removing a relevant part of the interfering nuclides. However, for some applications the direct measurement of Tc-99 in water samples without previous chemical separation is required. It is of great interest to verify which levels of Tc-99 can be reliably determined in presence of variable concentrations of Mo and Ru. We present a systematic investigation of the influence of Mo and Ru at various orders of magnitude on the background for the determination of Tc-99 in samples with different matrices.