Determination of technetium in99Mo/99m Tc-generators

The Tc budget in several ROTOP-generators was determined by neutron activation analysis (NAA) and UV-spectroscopy. The complete procedure included the preparation of the generator, elution cycle in 24 to 72 h intervals and evaporation of the eluates to dryness. The samples were aliquoted, irradiated in the reactor and analyzed via99Tc(n, n')99mTc→99Tc reaction as well as by UV-absorption due to pertechnetate. The most reliable method proved to be NAA including chemical separation from24Na by ion exchange after the complete decay of38Cl. The detection limit was 50 ppb (3 ng Tc), compared with the total amount of several 10−5 g down to 10−7 g Tc in the system and its fractions. The mass balance and the elution profiles obtained correspond very well to the theoretical values. The results permit further quantitative considerations on both elution kinetics and the generator system.