Magnetic molecularly imprinted polymer for the detection of rhaponticin in Chinese patent medicines

The magnetic molecularly imprinted polymers (MMIPs) had been synthesized for the selective extraction and clean-up of rhaponticin in Chinese patent medicines (CPM). The MMIPs were prepared via suspension polymerization, using Fe3O4 as magnetically component, rhaponticin as template molecule, acrylamide (AM) as functional monomers, styrene (St) as copolymer monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker in dimethyl sulfoxide porogen. The obtained MMIPs were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). High performance liquid chromatography (HPLC) was used for analysis the target analytes. The polymers were evaluated further by batch rebinding experiments. From the derived Freundlich isotherm (FI) equation their binding capacity and binding strength were determined. Structurally similar compound resveratrol and a reference compound kirenol were used for investing the selective recognition capability of MMIPs. The MMIPs were used as sorbents for selective pre-concentration of rhaponticin from CPM samples. The contents of rhaponticin for the four CPM samples were found to be 11.84, 3.35, 4.47, and 7.57 mu g g(-1), respectively, and the recoveries of spiked samples ranged from 77.82% to 91.00%. The prepared MMIPs could be applied to selectively pre-concentrate and determine rhaponticin in CPM samples. (C) 2012 Elsevier B.V. All rights reserved.