Synthesis and characterization of a surface imprinting silica gel polymer for the resolution of tetrahydropalmatine enantiomers

Abstract An L‐tetrahydropalmatine (L‐THP) imprinted silica gel polymer functionalized with aminated groups was prepared with surface imprinting technique by using L‐THP as template, grafted silica gel as support, methacrylic acid as functional monomer and ethylene glycol dimethyl acrylate as cross‐linker by solution polymerization. The optimum ratio of template, functional monomer, and cross‐linker were found to be 1:4:20 and the conditions of synthesis were 50°C for 18 h. The surface imprinting silica gel polymer of L‐THP was used as a sorbent for L‐THP adsorption and showed better adsorption capacity of L‐THP than that of non‐imprinted polymers. Then the surface imprinting silica gel polymer of L‐THP was filled into the cartridges as the adsorbents of solid‐phase extraction, and the mean recoveries of L‐THP and D‐tetrahydropalmatine were 70.1% and 17.1% with 2.8% and 3.0% of relative standard deviation, respectively.