Quantitative determination of trace concentrations of quercetin from prickly pear skin complex sample extracts by application of molecularly imprinted polymers

A molecular imprinted polymer-solid phase extraction technique was used for the selective extraction of quercetin from ultrasonicated extracts of prickly pear skins. This combination uses less energy and shorter extraction times which then prevent degradation of quercetin during extraction. Molecular imprinted polymer and non-imprinted polymer were prepared by employing acrylamide and 4-vinylpyridine binary functional co-monomers, but quercetin was omitted in the synthesis of the later. Both polymer particles were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. Effects of various parameters influencing the rebinding of quercetin onto polymers such as pH, contact time and initial concentration were investigated, and the optimum values were pH 2, 120 min and 100 mu mol L-1, respectively. The maximum adsorption capacity of quercetin by the molecular imprinted polymer was 16.5 mu mol g(-1) and 15.5 mu mol g(-1) for non-imprinted polymer. The method limits of detection and quantification for the molecular imprinted polymer after elution were found to be 2.6 +/- 0.1 mu g L-1 and 8.6 +/- 0.3 mu g L-1, respectively. A physisorption process was proposed from the pseudo-first-order kinetics, while a fit to Langmuir adsorption isotherm suggested a monolayer adsorption of quercetin onto sorbents. (C) 2017 Elsevier Ltd. All rights reserved.