| A cinchonidine-MAA system was utilized to test and validate an IR spectroscopy method for the characterization of the prepolymerization solution. Our results showed that ATR-FTIR spectroscopy is not sensitive enough to detect low levels of MAA that result from strong interactions with the template molecule or discern very weak bonding interactions that have a dramatic effect on polymer selectivity. ITC was proposed as a possible alternative to conventional spectroscopic techniques. The results from these experiments revealed that formation of the cinchonidine-MAA complex has a DeltaH fof -43.9 kcal/mol (RSD=3.19%), which indicates that the formation of the monomer-template complex is energetically favorable. A series of polymers containing different amounts of MAA and chromatographically were prepared and their selectivity determined. The selectivity values obtained for the 4:1 polymer (alpha = 24.4) was significantly higher than that of the polymer prepared with three equivalents (alpha = 13.6), equaling the number of functional groups, of MAA.; A discussion concerning basic theoretical parameters relating to solid-phase extraction was presented. Breakthrough volumes were determined for both cinchonidine and cinchonine on a cinchonidine-imprinted polymer. Scatchard plots were used to assess the binding occurring within each polymer and allowed for the determination of both the binding constant as well as the number of binding sites present. Analysis of the cinchonidine scatchard plot revealed the presence of two distinct classes of binding sites, while the cinchonine plot showed the presence of only one class of binding sites. It was found that the imprinted polymer possesses 13.9 mumol/g polymer of these selective sites, which have a binding constant of 4.42 x 106 mol-1. |
