Multi-templates Molecularly Imprinted Polymer for the Specific Solid- Phase Extraction of Saponins from <i>Panax notoginseng</i> Herbal Extract

A novel multi-templates molecularly imprinted polymer (MIP), using three saponins mixture (notoginsenoside R1 (R1), ginsenoside Rg1 (Rg1) and ginsenoside Rb1 (Rb1)) as the template, was synthesized by precipitation polymerization and used as the solid-phase extraction (SPE) sorbent. The synthesis was optimized by using different functional monomers, polymerization solvents, cross-linkers, and molar ratios of template:functional monomer:cross-linker. The resulting MIPs were evaluated by transmission electron microscope (TEM) and adsorption experiments, exhibiting uniform spherical morphology, high adsorption capacity and rapid kinetics for the rebinding of template. The adsorption capacity of the imprinted polymers to the template was more than 2.0-folds that of non-imprinted polymers (NIPs). MIPs were successfully applied to the SPE for the extraction of R1, Rg1 and Rb1 from the Panax notoginseng herb extract. Mean recoveries of R1, Rg1 and Rb1 determined by HPLC (highperformance liquid chromatography) were in the range of 80.7–82.4% with relative standard deviations (RSDs) less than 3.2%. These results reveal that the multi-templates MIPs as SPE sorbent have good applicability to selectively extract a group of saponins from complex samples. Keywords: Ginsenoside Rg1, ginsenoside Rb1, multi-templates molecularly imprinted polymer, notoginsenoside R1, precipitation polymerization, Panax notoginseng, solid-phase extraction.