A method for separating bound versus unbound label during radioiodination.

An inexpensive, highly effective, and safe method for the removal of bound versus unbound label during radiolabeling of proteins is described. The technique employs the use of membrane ultrafiltration technology and returns in one step a highly reproducible product of quality superior to that attained by gel chromatography. Advantages of this technique are a reduction in the quantity of liquid and solid radioactive waste and a significant limitation of potentially harmful manipulation and exposure times.