Shelf-life of 99mTc(Sn)-pyrophosphate

The effect of the preparation conditions on the in vitro stability of 99mTc(Sn)-pyrophosphate kit solution has been examined. To extend the self-life of the preparation different methods of protection were tested. Nitrogen purging stabilizes the kit for at least 6 h after labeling when the content of 99mTc-pertechnetate raises to about 5%. However, this method is in effective in the presence of hydrogen peroxide. The protecting ability of two chemicals was also determined. Gentisic acid gave good results. In the presence of 50 μg of gentisic acid per ml of the kit the content of pertechnetate was 1-2% throughout the examined time interval. To eliminate the influence of hydrogen peroxide (6 μg per ml of the kit) about 100 μg of gentisic acid is needed. N, N'-diphenyl-p-phenylene-diamine (DPPD) performs some protecting effect only when used in the samples protected by nitrogen purging. However its protecting ability is lower that the case of gentisic acid. (author). 3 refs., 1 fig., 2 tabs