Capture and Purification of Polyphenols Using Functionalized Hydrophobic Resins

Adsorption can be an effective way of purifying polyphenols from complex mixtures. However, polyphenols may be present in small concentrations, making it difficult to selectively adsorb them onto standard hydrophobic resins and obtain appreciable adsorption. In this work, nonfunctionalized hydrophobic resins (Amberlite XAD-7HP, XAD-16) are compared with functionalized resins with imidazole (Biotage RENSA PX) and pyridine (RENSA PY) in terms of capacity and selectivity toward p-coumaric acid, trans-resveratrol, and naringenin. The obtained results indicate that, due to hydrogen bonding, the functionalized resins provide more capacity (e.g., 80 mg·g^-1 vs 11.3 mg·g^-1 for trans-resveratrol) and up to five times more selectivity than standard resins. Despite such strong affinity, at low pH, the isotherm slope can decrease up to four times when compared to the XAD resins for the same ethanol content, making desorption easier. The included isotherm data is enough to model any chromatography dynamic simulation for the studied compounds.