Adsorption Isotherms of Quercetin and Catechin Compounds on Quercetin-MIP*

A molecular imprinted polymer(MIP) was prepared with quercetin as the template and methacrylic acid(MAA) as the functional monomer. Acetonitrile and methanol were used as the porogen with ethylene glycol dimethacrylate (EGDMA) as the crosslinker and 2,2′-azobis(isobutyronitrile) (AIBN) as the initiator. The experimental parameters of the equilibrium isotherms were estimated via linear and nonlinear regression analyses. The linear equation as the functions of the adsorption concentration of the single compound in its solution and the competitive adsorption of the single compound in its mixed compounds solution was then expressed, and the adsorption equilibrium data were correlated to Langmuir and Freundlich isotherm models. The mixture compounds show competitive adsorption on the specific binding sites of quercetin-MIP. Furthermore, the competitive Langmuir isotherms were applied to the mixture compounds. The adsorption concentrations of quercetin, (+) catechin (+C), and (-) epicatechin (EC) on the quercetin molecular imprinted polymer were compared. The quercetin-imprinted polymer shows extraordinarily higher adsorption ability for quercetin than for the two catechin compounds that were also assessed.