Use of 99mTc from a commercial 99Mo/99mTc generator as yield tracer for the determination of 99Tc at low levels

The concentrations of 99Tc and impurity radionuclides in the 99mTc tracer solution obtained from a commercial 99Mo/99mTc generator were measured by gamma spectrometry and liquid scintillation counting. 99Mo and 103Ru were found in the 99mTc eluate. A simple separation using two extra alumina cartridges was investigated to purify the eluate to obtain a suitable 99mTc tracer with low 99Tc concentration. The activity ratio of 99Tc/99mTc in the prepared 99mTc solution is lower than 15×10−9, which is higher than the theoretical ratio of less than 10×10−9. The possible reason is discussed. The 99Tc in the 20 kBq spiked 99mTc tracer was found to be less than 0.3 mBq, which is lower than the detection limit of the radiometric method used for environmental samples. The purified 99mTc eluate is used as yield tracer for the determination of low levels of 99Tc in environmental samples.