Uniformly sized molecularly imprinted polymer for (S)-naproxen retention and molecular recognition properties in aqueous mobile phase

A uniformly sized molecularly imprinted polymer (MIP) for (S)-naproxen has been prepared by a multi-step swelling and polymerization method using 4-vinylpyridine (4-VPY) and ethylene glycol dimethacrylate (EDMA) as a functional monomer and cross-linker, respectively. We optimized the preparation method of the MIP by changing the molar amounts of the template molecule and functional monomer. Further, we examined the effects of organic modifier type, column temperature and flow-rate on the retentivity and enantioselectivity for naproxen using a mixture of phosphate buffer and organic modifier (acetonitrile, ethanol and 2-propanol) as an eluent. When the amounts of (S)-naproxen, 4-VPY and EDMA used were 4, 6 and 25 mmol, respectively, the enantioselectivity and resolution for naproxen were good despite the shorter retention. When acetonitrile was used as an organic modifier, the highest column efficiency was obtained for the separation of naproxen enantiomers. With regard to the effects of column temperature and flow-rate, the column performance was improved by elevating a column temperature and decreasing a flow-rate.