Molecularly imprinted polymers targeting quercetin in high-temperature aqueous solutions

Molecularly imprinted polymers (MIPs) targeting quercetin were prepared from 4-vinylpyridine and ethylene dimethacrylate (EDMA) under various solvent systems with the aim to form MIPs with high recognition for the quercetin molecule in aqueous systems at high temperature. A MIP prepared from the three-component solvent mixture of THF/H2O/MeOH showed potential in its application for the determination of quercetin in plants (onion). The polymer particles before and after washing were characterized by infrared spectroscopy and thermogravimetric analysis. Surface morphology was recorded by scanning electron microscopy. The binding capacity of the MIPs was investigated at 25 and 84 °C, respectively, in batch mode. Parameters, including the influence of pH, extraction time and binding capacity, were evaluated. The slopes for the effect of extraction time revealed that the mass transfer of the analytes was higher at 84 °C than at 25 °C. Also, the binding capacity for the most promising MIP and its corresponding NIP was higher at 84 °C. The binding capacity for the MIP was ∼30 μmol g−1 at 25 °C and ∼120 μmol g−1 at 84 °C, while for the corresponding NIP, it was ∼15 and ∼90 μmol g−1, at 25 and 84 °C, respectively. A demonstration of MIP selectivity at higher temperature using standard solutions of selected flavonols showed that the MIP still retained its selectivity for quercetin. Similar selectivity was observed when preliminary application studies on aqueous yellow onion extracts were investigated.