Technical problems in equilibrium dialysis

It was found that several DNP-hapten preparations contained low levels of contamination with radioactive, weakly bound impurities which could not be removed by routine methods. This contamination resulted in artificially low values for antibody affinity and artificially high values for the heterogeneity index. A mathematical model for the binding of contaminated hapten by homogeneous antibody was developed. This model predicted that the degree of distortion would be minimized by the use of large ‘outside’ volumes and low antibody concentrations for equilibrium dialysis measurements. Experimental data consistent with these predictions were obtained.