99 the 34 parent 34 radionuclide is maintained on a containerized support medium usually alumina and when eluted with the proper eluant usually saline technetium 99m in the form of pertechnetate ion 99m tco 4 sup u2296 is generated see for example u s pat nos 3 369 121 and 3 920 995 various complexing also known in the art as chelating agents can be used in the process of this invention the complexing agent should be pharmaceutically acceptable and able to keep m in solution after the decomposition of complex ii exemplary complexing agents are ethylene glycol bis u03b2 aminoethyl ether n n 39 tetraacetic acid egta ascorbic acid sulfosalicyclic acid and other complexing agents that will not interfere with the synthesis of complex i at an acceptable ph 2 7 the particular reaction conditions needed for the ligand exchange reaction of this invention will depend on the particular complex of formula ii being used in general however the reaction will be run at a temperature of about 30 u00b0 to 180 u00b0 c preferably about 30 u00b0 to 130 u00b0 c after the ligand exchange reaction is complete water can optionally be added to the reaction mixture the water may be desirable to reduce the saline concentration of the preparation to isotonicity with blood the complexes of formula ii exist as stable solid salts that can be conveniently formulated by manufacturers to allow for a minimum number of manipulative steps by the medical technicians responsible for the preparation of cationic lipophilic complexes of technetium 99m formula i the most advantageous formulation comprises a metal complex of formula ii and a source of anion as discussed above it may also be desirable to include a complexing agent in the formulation the concentration of.