Preparation And Evaluation Of The Molecularly Imprinted Coatings For Capillary Electrochromatography

One monomer molecularly imprinted polymer coatings were first synthesized in fused silica capillary columns with2-methacrylamidopropyl methacrylate (MAM) as single functional monomer in addition to a cross-linking monomer. This approach eliminates variables such as choice of functional monomer and crosslinker, the ratio of functional monomer/crosslinker, and the ratio of functional monomer/template which normally complicate the MIP design. Furthermore, for the molecular recognition in OMNiMIPs, the incorporation of the functional monomer into the cross-linker backbone reduces not only the conformational flexibility of the binding site, but also the entropic effect associated with binding interactions.Since MAM may generate no or little EOF, a strategy of precursor of polymerization, which does not interfere with the formation of defined imprints, was used to introduce an ionizable functional monomer to generate a stable electroosmotic flow for electrochromatography (CEC) by post-polymerization hydrolization. The resulting MAM-based open-tubular imprinted capillary was able to separate enantiomers by means of CEC. The resolution of enantiomers separation achieved on S-amlodipine-imprinted capillary was up to16.1. The strong recognition ability (selectivity factor was3.23) and high column performance (theory plates was26,053plates m-1) of template were obtained. The MIP coatings were also prepared using either S-naproxen or S-ketoprofen as template molecule. The resolutions of enantiomers separation were2.20and4.56, respectively. The results illustrate that the synthesis of MIP using one monomer is not only an experimental-simplified process, but also an approach to producing chiral stationary phase with high efficiency and selectivity.Surface imprinting is an approach that is initiated from a preformed polymer or the surface of a solid support. The resulting MIP shell overlayer allows improved accessibility of the sites, while the properties of the core material were also preserved due to not radically modifying the permeability of the resulting material. A MIP coating grafted to a trimethylolpropane trimethacrylate (TRIM) core material for capillary electrochromatography (CEC) was reported. The core monolith was prepared with a solution of20%(w/w) TRIM in a mixture of porogen and a polymerization precursor, which can generate a stable electroosmotic flow due to the formation of ionizable groups after post-polymerization hydrolization. Graft polymerization took place on the resultant TRIM monolith with a mixture of (S)-amlodipine, methacrylic acid and ethylene glycol dimethacrylate. Strong recognition ability (selectivity factor was5.83) and high column performance (up to10,785plates/m) of the template were obtained on the resulting grafted imprinted monolith in CEC mode. The resolution of enatiomers separation achieved on the (S)-amlodipine-imprinted column was up to7.99. The MIP coatings grafted to TRIM core metarials were also prepared using either S-ofloxacin or S-zopiclone as template molecule. The resolutions of enantiomers separation were4.97and1.22, respectively. These results suggest that this technique of grafted polymerization allows the imprints to be directly created on the surface of the monolithic material using a minimum amount of template and is a good alternative to prepare CEC-based monolithic MIPs.