A convenient method for the determination of non-specific binding in commercially available solid phase iodine...

57Co-cyanocobalamin is substituted for iodine labeled antigen in three commercially available solid phase radioimmunoassay kits to evaluate the extent of non-specific binding by determination of the supernatant and residual fraction of unbound ligand and thus obtain a value for corrected binding throughout the range of the calibrated standard curve. In the present state of technology correction appears to have a trifling effect on the overall accuracy of the assay; however, the method as described allows the laboratorian to confirm for himself when testing a new product.