Measurement of the continuous distribution of binding sites in molecularlyimprinted polymers

Reported is the first affinity spectrum (AS) [number of binding sites (N) v s. association constant (K)] for a non-covalently imprinted polymer. The AS method yields the distribution of sites over a continuous range of binding constants and characterizes the heterogeneity present in imprinted polymer s better than current methodologies. To demonstrate the generality of the A S method, the distributions for three different imprinted polymers (two of which were taken from the literature) were calculated from their respective binding isotherms. The shapes of the distribution curves were different ye t consistent with the respective covalent or non-covalent imprinting mechan isms. Finally, the binding parameters derived from the AS method were compa red with those determined by the more common Scatchard analysis and were in general agreement.