Preparation of deep eutectic solvent-based hydrophilic molecular imprinting resin for separation and purification of kaempferol from tea

Kaempferol (KAE) has good biological activity, it is important to isolate kaempferol from tea. In this study, hydrophilic molecularly imprinted resin (MIRs) with specific selectivity and environmental friendliness were prepared in water phase using aminophenol formaldehyde resin as a carrier for adsorption of KAE. During the preparation process, deep eutectic solvents (DES) were used as co-solvents for pore makers and templates to improve the specific surface area of MIRs. DES replace the use of organic solvents and make the whole process green. Due to their high selectivity (imprinted factors =3.82) and aqueous phase compatibility, the MIRs can specifically recognize and extract KAE from aqueous phase. In comparison with reported adsorbent materials, MIRs have better specific ability to extract KAE and higher adsorption capacity (Q_e=603.43 mg/g). Mechanistic studies have demonstrated that the main forces involved in adsorption are hydrogen bonding and electrostatic attraction. A method combining solid phase extraction and high-performance liquid chromatography was developed for the determination of KAE in tea. The developed method showed good linearity (R²=0.9992), lower limit of detection (0.29 μg/mL) and excellent relative standard deviation (RSD ≤ 3.9 %) The prepared MIRs proved to be a green and high adsorption capacity with promising applications in the purification and separation of alkaloids from natural products.