The effect of carrier technetium in the preparation of 99mTc-human serum albumin.

Accumulation of daughter 99Tc in 99Mo-99mTc generator systems may adversely affect the preparation of certain 99mTc radiopharmaceuticals. In a study of the effect of "carrier" technetium on the radiochemical purity of 99mTc-human serum albumin, varying amounts of 99Tc were added to a commercially available electrolytic kit. The maximum amount of 99Tc that could be added to such a kit and still maintain radiochemical purity above 90% was about 3 X 10(15) atoms. When kits containing 10(16) 99Tc atoms were electrolyzed for the conventional 42 sec, the radiochemical purity was only 50.8%. However, when the electrolysis time was varied, it was found that electrolysis for 80 sec yielded a product with greater than 90% radiochemical purity. Four solutions to the problem created by the 99Tc carrier effect are described.