Separation of free and protein-bound ligands in the radioimmunoassay by gel filtration-centrifugation.

The application of gel filtration-centrifugation to the separation of free and protein-bound ligands in radioimmunoassay is described. The method is simple and rapid. A large number of samples can be handled simultaneously and the bount radioactivity is directly transferred to the scintillation vial. Using a 9 X 36 mm column of Sephadex G-50 (coarse), 400 mul of the reaction mixture can be separated during 2 min centrifugation.