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.