Preparation Of Molecular Imprinted Monolithic Column And Its Research Of Molecular Recognition

The molecular imprinted monolithic column with the advantages of simple preparation, good hydrodynamic characteristic, low flow resistance as well as the fast transfer has potential applications in the separation and analysis of the medicine. In this study, molecular imprinted polymers and monolithic columns for caffeine, repaglinide and melamine were prepared by the methods of bulk polymerization and in-suit polymerization, using molecular imprinted technique. The identifying and binding capacities were studied by the static equilibrium adsorption test. The molecular imprinted polymer was used as solid-phase extraction adsorbents for solid-phase extraction column to extract the caffeine in tea. The molecular imprinted monolithic column was a novel technology for chromatographic stationary phase in the high performancd liquid chromatography. The MIP column was used to separate repaglinide and its enantiomer and to detect the content of melamine in dairy.The origin, principle, preparation and application of molecular imprinted technique were introduced in this paper.A molecular imprinted polymer highly selective for caffeine was prepared by molecular imprinted technique with methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross linker.In this preparation process, the molar ratio of these three matters was 1:4:20 with acetonitrile as solvent. Scatchard analysis indicated that there were two classes of recognition sites in caffeine-imprinted polymer, which had different affinity to caffeine. The dissociation constants of high-affinity adsorption sites and low-affinity adsorption sites were 5.88mmol/L and 20mmol/L. Caffeine MIP was used for the preparation of solid-phase extraction column and detect the extraction of caffeine in tea by high performance liquid chromatography. The average recovery was 82.1%~90.6% and the relative standard was less than 5%.A molecular imprinted polymer highly selective for repaglinide was prepared by molecular imprinted technique with acrylamide as functional monomer and ethylene glycol dimethacrylate as cross linker. In this preparation process, the molar ratio of these three matters was 1:4:20 with acetonitrile as solvent. Scatchard analysis indicated that there were two classes of recognition sites in repaglinide-imprinted polymer,which had different affinity to repaglinide. The dissociation constants of high-affinity adsorption sites and low-affinity adsorption sites were 1.22mmol/L and 7.69mmol/L. The molecular imprinted monolithic column of chiral drugs repaglinide was prepared by the methods of in-suit polymerization, which can be application in the separation and analysis of the repaglinide. In this experiment, the mobile phase was acetonitrile: water=9: 1(containing 0.05% acetic acid), the flow rate was 0.5mL/min and the UV detection wavelength was 245nm.A molecular imprinted polymer highly selective for melamine was prepared by molecular imprinted technique with methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross linker. In this preparation process, the molar ratio of these three matters was 1:5:20 with toluene/dodecanol as porogen. A sensitive method was developed for the determination of melamine in dairy products by the melamine molecular imprinted monolithic column, which was a novel technology for chromatographic stationary phase in HPLC. By researching the influence of different mobile phases, content of melamine in dairy was detected by HPLC. In this experiment, the mobile phase was 10% methanol-water: 0.1% acetic acid-water=5: 95 and the flow rate was 0.5mL/min. The linear range of melamine was 1.0μg/mL～100.0μg/mL(r=0.9987). The average recovery was 87.0%~100.5% and the relative standard was less than 5% (n=6). The quantitative limit of this method was 1.0mg/kg, so it was able to satisfy the limit of determination requirements of melamine in dairy products.