Molecular imprinting in ionic liquid-modified porous polymer for recognitive separation of three tanshinones from Salvia miltiorrhiza Bunge

Five ionic liquid-modified porous polymers with different imidazolium-based functional groups were obtained. A molecular imprinting technique was introduced to form the ordered functional groups in the porous structure. The adsorption isotherm was applied to investigate the interactions between the polymers and target compounds: cryptotanshinone; tanshinone I; tanshinone IIA. Thorough comparison revealed that the polymer with a carboxyl group possessed the highest reorganization of the three compounds. After that, the obtained polymer was applied as the sorbent in the solid-phase extraction process to separate the target compounds from methanol extract. The loading volume of extract solution on the sorbent was determined by adsorption isotherm equation and practical test. Under optimized washing and elution conditions, 0.35 mg/g of cryptotanshinone, 0.33 mg/g of tanshinone I, and 0.27 mg/g of tanshinone IIA from plant were obtained by quantitative HPLC analysis. Moreover, six commercial functional drinks containing tanshinones were purified and analyzed.