On the Use of99Mo/99mTc Generators in the Analysis of Low Levels of99Tc in Environmental Samples by Radiochemical Methods

Abstract

The analysis of low levels of the long-lived fission product 99Tc in environmental samples presents special challenges, particularly with respect to the selection of an appropriate and practicable chemical yield tracer. Of all the tracers available, 99mTc eluated from 99Mo/99mTc generators appears to be the most practicable in terms of availability, ease of use and cost. These factors have led to an increase in the use of such generators for the provision of 99mTc as yield tracer for 99Tc. For the analysis of low levels (<1Bq/m3 or kg) of 99Tc in environmental samples, consideration must be given to the radiochemical purity of the tracer solution with respect to contamination with both 99Tc and other radionuclides. This paper details investigations carried out in relation to the use of 99Mo/99mTc generators for the provision of 99mTc for use as yield tracer in the analysis of low levels of 99Tc. The results of the study indicate that special care must be taken with the radiochemical purity of the 99mTc solution. Analysis of eluates from a number of such generators indicates the presence of 103Ru and 99Tc in levels that could produce inaccuracies in the analysis of low levels of 99Tc. Results are presented and the findings discussed with reference to low level 99Tc analysis by radiochemical procedures and beta counting.