Technetium pyrophosphate: a mixture - preparation of Tc(III) and Tc(IV) pyrophosphates and their comparative biologic properties

A method is described for the selective preparation of either Tc(III) or Tc(IV) pyrophosphate. Controlled-potential electrolysis was used as the labelling procedure to obtain tin-free preparations in the chosen oxidation state. The two complexes were identified by polarography and their biological distributions were studied in mice. At both carrier and tracer concentrations the trivalent complex had slower blood clearance and higher gastric uptake than the tetravalent. There was no difference in bone uptake between tracer doses of Tc(III) and Tc(IV), whereas bone uptake of the Tc(III) compound was lower with carrier doses. (U.K.)