Technetium-99m-sulfur colloid. In vitro studies of various commercial kits

The quality of five commercial 99mTc-sulfur colloid kits was compared. A number of chemical parameters, which characterize the colloids, was used in order to study the influence of variations in the preparation procedures and storage of the final products. The differences between the kits could mainly be referred to the order of addition of the reagents. The quality was generally unaffected by variations in time-intervals during preparation. However, a certain heating time was necessary for optimal labeling. Variations in quantities of acid and buffer were found to influence the particle size as well as the content of unreacted pertechnetate. No deterioration in quality by storage was observed; on the contrary in some cases the content of free activity decreased.