Improved fitting of radioimmunoassay data by Scatchard analysis

We present a model of radioligand binding, based on the approach of Scatchard, that improves the fit of the data to the standard curve by allowing for the presence of radioactivity which cannot be bound by the antibody and using this non-specific binding as an additional fitting parameter. Further, it accounts for the specific activity (mass contribution) of the radioligand. Our procedures aim to: (1) minimize the squared error of the fit rather than to maximize the correlation coefficient; (2) provide assistance in the design and debugging of routine radioimmunoassay data; and (3) help assure the quality of results produced by established assay systems.