The ultrapurification of indium-111 for radiotracer studies

We have developed a procedure for the ultrapurification of 111In. A dried sample of 111InCl3 is dissolved in 1 ml of a freshly prepared KI solution of 4% in 4 N H2SO4. After 3 ml of anhydrous diethylether has been mixed well with the aqueous and centrifuged for 5 minutes at 2000 X g, the iodide salt of 111In is recovered with the organic solvent layer at approximately 92% of the original radioactivity. The organic phase is evaporated under a gentle stream of inert gas. After the sublimation of iodine, 111In is dissolved in a solvent of choice. The extraction is highly selective for In and separates it from, at least, Fe, Al, and Zn, principle associated cationic contaminants.