Radiolabeling of affinity-purified goat anti-carcinoembryonic antigen immunoglobulin G with technetium-99m.

Affinity-purified goat anti-carcinoembryonic antigen immunoglobulin G was labeled with 99mTc, utilizing stannous tartrate as the reducing agent. The radiochemical yield of labeled antibody ranged from 18 to 37% and was inversely proportional to the initial quantity of pertechnetate ion used. Yields up to 60% could be obtained using small amounts of pertechnetate. The 99mTc-labeled anti-carcinoembryonic antigen immunoglobulin G preparations had a specific activity range of 1 to 6 microCi/microgram protein and had 60% or greater immunoreactivity. Human serum albumin and goat immunoglobulin G were used as model systems to evaluate labeling parameters and analytical methods.