Determination of the oxidation state of 99mTc in complexes with MDP and DTPA.

The oxidation state of technetium-99m, reduced by concentrated hydrochloric acid and evaporation until dryness, was determined by radiochromatography. The dry deposits of reduced 99mTc were allowed to react with DTPA and MDP with and without antioxidants present. The formation of 99mTc(IV)-DTPA and 99mTc(IV)-MDP complexes and the influence of the antioxidants gentisic and ascorbic acids were studied by radiochromatography and by biodistributional studies in rabbits. 99mTc(IV)-MDP complexes thus formed were demonstrated to have the same biodistribution in rabbits as 99mTc-MDP complexes formed by a conventional stannous reduction kit technique.