Process for concentrating technetium-99m

A method of increasing the radioactive concentration of technetium-99m in an aqueous solution containing the technetium-99m as pertechnetate ion TcO.sub.4.sup.- which method consists essentially of the steps of:

• (1) if the solution is not already acid, acidifying it,
• (2) contacting the resulting acid solution with a bifunctional ion-exchange material which is an anion-exchanger under acid conditions and a cation-exchanger under alkaline conditions, the pH of the solution being such that the bifunctional ion exchange material in contact with it acts as an anion-exchanger and adsorbs pertechnetate thereon, and recovering the acid bifunctional ion-exchange material with pertechnetate ion carried thereon and an acid liquid substantially free of pertechnetate ion,
• (3) contacting the material resulting from step (2) with an aqueous alkaline liquid, of smaller volume than the aqueous starting solution treated in step (1), the pH of the aqueous alkaline liquid being such that the bifunctional ion-exchange material in contact therewith acts as a cation-exchanger and releases pertechnetate adsorbed thereon, and recovering an aqueous alkaline solution containing pertechnetate ion, and
• (4) neutralizing the alkaline solution recovered in step (3) to obtain an aqueous solution containing pertechnetate ion at a higher concentration than the starting material.