Molecular imprinted Nylon-6 stir bar as a novel extraction technique for enantioseparation of amino acids

Abstract

The flexibility and simplicity of stir bar sorption extraction (SBSE) have been combined with the selectivity of molecularly imprinted polymers (MIP). Stir bars were coated reproducible with a 160-μm film formed from a formic acid solution of Nylon-6 polymer either nonimprinted or imprinted with L-glutamine. Time sorption profiles were measured for the extraction of L-glutamine at the concentration of 20–500 μmol L⁻¹ levels with both types of films in order to compare sorption characteristics. The results indicated that the MIP coated layer showed remarkable high affinity towards L-glutamine and equilibrium adsorption was attained rapidly (60 min) in contrast to conventional bulk molecularly imprinted polymer in which equilibrium adsorption was normally attained after 16–24 h. The imprinted stir bar was also shown a high degree of selectivity toward L-glutamine compared to its isomer and analogues, while a reference stir bar prepared without the imprinting molecule was not shown any selectivity towards the enantiomers. Evidence was also presented by FT-IR analysis that the amide-hydrogen-bonding interaction between L-glutamine and amide groups in MIP-film was originated for L-glutamine recognition. The scanning electron microscope photographs showed that visible pores structure could be detected in the L-glutamine imprinted Nylon-6 film. Compared with traditional MIP and SBSE, the MIP-coated film showed not only the high selectivity, but also the rapid equilibrium adsorption. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008