Study On Preparation And Application Of Estradiol-imprinted Microspheres Using Modified Precipitation Method

Molecularly imprinted polymers (MIPs) are tailor-made synthetic polymer-receptors for target molecules (template). MIPs have advantages such as predetermination, recognition and practicability,physical robustness, high strength, resistance to elevated temperatures and pressures, and inertness towards organic solvents, acids or bases. MIPs have been widely used in trace analysis of organic pollutants.Recently, many polymerization methods are developed to prepare MIPs. Precipitation polymerization is the widely used method for the production of high quality, uniform and spherical imprinted microspheres. However, the porogen used in classic precipitation polymerization is high, which leads to environmental pollution and increases the cost. In order to overcome the disadvantage of classic polymerization method, a new polymerization method, named modified precipitation polymerization (MPP) method, was established in our lab. In this thesis, MPP was used to prepare narrowly dispersed molecularly imprinted polymeric microspheres for estradiol. By optimizing the preparing conditions, one estradiol imprinted microsphere with the best binding characters were used in off-line molecularly imprinted solid-phase extraction (MISPE) to determine the trace amount of estradiol in biological and enviromental samples (chicken, pork, fish, orange juice and tap water). This thesis includes:1. Estradiol imprinted polymeric microspheres were synthesized by modified precipitation polymerization. Frontal chromatography and selectivity experiment were used to determine the binding capability and binding specificity of different imprinted microspheres.2. One microsphere that had the highest binding selectivity and capability was used as solid-phase extraction (SPE) sorbents for direct extraction of estradiol from different biological and environmental samples (chicken, Orange juice, fish , pork and tap water). The extraction protocol was optimized. And under the optimum conditions MIPs can selectively recognize, effectively trap and pre-concentrate of estradiol over a concentration range of 0.5-10μmol/L. The intra-day and inter-day RSD are less than 1.73% and 2.6% respectively. The limit of quantification was 0.05μmol/L. Under the optimal condition, MISPE recoveries of spiked chicken, orange juice, fish , pork and tap water were 71.16%, 83.75%, 75.25%, 74.98% and 89.26% respectively. Compared with C18 SPE, better HPLC separation efficiency and higher recoveries were achieved after MISPE.It was showed that E2-imprinted microspheres prepared by modified precipitation polymerization have good affinity and selectivity for the E2, and can be used in MISPE to determine trace amount of estradiol in biological and enviromental samples. This methodology is useful for accurate determination of estradiol levels in the environmental and biological matrices.