Preparation of technetium-99m-humic complex by ligand exchange from hexakis (thiourea-S)technetium(III) complex

The preparation of technetium-99m-humic complex without presence of any metal reductant was studied. For the preparation of Tc-HA complex by ligand substitution hexakis(thiourea-S)technetium(III) complex was used as a precursor. Ligand exchanging reaction was studied with two different humate/thiourea concentration ratios. After mixing of [^99mTc(tu)₆]³⁺ complex with natrium humate under a nitrogen atmosphere a formation of technetium humate wasobserved. The determination of reaction products was performed by combination of gel and paper chromatography. Reaction yields are dependent on humate/thiourea concentration ratio and reaction time. Tc-HA complex was obtained with the highest yield of 62%. Reaction mixture also contains a technetium dioxide as a side product of exchanging reaction and other technetium species, which are also discussed. Oxidation state of technetium in prepared Tc-HA complex is apparently unchanged.