Molecularly imprinted polymers with ionic liquid as the functional monomer for selective solid-phase extraction of gastrodin

Abstract

Gastrodia elata is a famous traditional herb. It is a challenging task to efficiently separate the active ingredient Gastrodin (p-hydroxymethylbenzene-β-D-glucopyranoside) from gastrodia elata by simple procedure. According to the results of computer molecular simulation & UV-vis spectroscopy, water-soluble 1-vinyl-3-tetradecylimidazole bromide([C14VIM + ] [Br -]) was selected as the best ionic liquid functional monomer compared with methacrylic acid(MAA), acrylic acid(AA), 3-(2-carboxyethyl)-1-vinylimidazolium bromide ionic liquid (imidazole propionate, [COOHpvimBr]) and dehydroabietic acid [2-(acryloyloxy)ethyl] ester (DAAEE). The force between [C14VIM + ] [Br -] and GAS (with multiple hydroxyl groups) is stronger than other monomers with more polar groups. The molecular imprinted polymers (MIPs) and non-molecular imprinted polymers (NIPs) withhigh selectivity to gastrodin(GAS) were synthesized utilizing ([C14VIM + ] [Br -]) as a novel functional monomer. In addition, surface molecular imprinted polymers (SMIPs) and surface non-molecular imprinted polymers(SNIPs) supported on silica gel were also prepared. These polymers were characterized by infrared spectrum, scanning electron microscope, specific surface area tester and thermosgravimetric analyser(TGA). The adsorption performance of the MIPs and NIPs was investigated by adsorption kinetics experiment and static adsorption experiment. By Molecular Imprinting-SPE extraction(HPLC), the content of gastrodin in eluent (70% ethanol) was significantly increased compared with it in plant extract, which is better than that of SMIPs-SPE. The recoveries of the spiked samples for the GAS ranged from 97.75-103.43% with relative standard deviation values lower than 2.88%. The molecular imprinted polymer was a potential separation material for gastrodin.