Electrophoretic determination of charge on carrier-free 99mTc-labeled complexes.

A new method for determining the charge on carrier-free 99mTc-labeled complexes is described. This method and mixed-ligand experiments were used to determine if the charge on the technetium 99m complex of N-(2,6-dimethylphenylcarbamoylmethyl)iminodiacetic acid (I) is - 1 and if the ligand to technetium ratio in the complex is 2:1. The preparation of an iodinated analog (II) of I and its 99mTc-labeled complex is described, as is the biodistribution of the 99mTc-labeled complex in mice. The synthesis of the 51Cr(III)- and 57Co(III)-labeled complexes also are described. The net biliary excretion in mice of both the 99mTc- and 51Cr-labeled complexes of II was significantly greater than that of the 99mTc-labeled complex of I.