Preparation of molecularly imprinted polymers for warfarin and coumachlor by multi-step swelling and polymerization method and their imprinting effects

Abstract

Monodisperse molecularly imprinted polymers (MIPs) for warfarin (WF) and coumachlor (CC), MIPWF and MIPCC, respectively, were prepared using 4-vinylpyridine (4-VPY) as a functional monomer and ethylene glycole dimethacrylate (EDMA) as a crosslinker by multi-step swelling and polymerization. Six kinds of MIPWF, MIPWF1 − MIPWF6, were prepared varying the concentrations of WF and 4-VPY, while maintaining the EDMA concentration constant, and their retention and molecular recognition properties were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase in LC. In addition to shape recognition, hydrogen bonding, ionic and hydrophobic interactions could affect the retention and molecular recognition of WF on MIPWF, and ionic interactions seem to govern the retention and molecular recognition of WF above mobile phase pH 6 associated with higher molar ratio of 4-VPY to EDMA. Furthermore, MIPCC was prepared under the same conditions with MIPWF6, which gave the highest imprinting factor for WF. WF could be recognized more strongly on MIPCC than MIPWF6, and the imprinting factors of WF on MIPWF6 and MIPCC, respectively, are 2.68 and 5.03 using 20mM sodium phosphate buffer − acetonitrile (30/70, v/v)(final pH 6.1) as the mobile phase. This result indicates that the use of CC as a template molecule instead of WF could be useful for getting a higher imprinting factor for WF and for avoiding the leakage problem in the assay of WF in LC.