Preparation And Application Of The Novel Molecularly Imprinted Polymers

Molecular imprinting is known as a technique for generating tailor-made recognition sites with memory of the shape, size and functional groups of the template molecules, which is endowed with the characteristics of predetermination, specific recognition and practicability. In recent years, molecular imprinting technique has become a hot-point in scientific research, especially in the domain of pretreatment of complex biological, food and environmental samples, chromatographic separation and chemical sensor. In this paper, we prepared the molecularly imprinted polymers with high selectivity and applied them to determine the environmental pollutants benzophenones and bisphenols.1. This work reports the preparation of molecularly imprinted polymer particles for the selective extraction and determination of four benzophenones from aqueous media. The polymer was prepared by using 4-vinylpridine as functional monomer, ethylene glycol dimethacrylate as cross-linker, acetonitrile as porogenic solvent and 2,2’,4,4’-tetrehydroxybenzophenone as template. Good specific adsorption capacity (Qmax=27.90 mol g-1) for 2,2’,4,4’-tetrehydroxy benzophenone was obtained in the sorption experiment and good class selectivity for 2,2’,4,4’-tetrehydroxy benzophenone,2,4-dihydroxy benzophenone,2,2’-dihydroxy-4-methoxy benzo-phenone and 2,2’-dehydroy-4,4’-dimethoxybenzophenone was demonstrated by the chromatographic evaluation experiment. Factors affecting the extraction efficiency of the molecularly imprinted solid-phase extraction procedure were investigated systematically. An accurate and sensitive analytical method based on the molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography and diode array detection has been successfully developed for the simultaneous determination of four benzophenones from tap water and river water with method detection limits of 0.25-0.72 ng mL-1. The recoveries of benzophenones for water samples at two spiking levels (500 and 5000 ng mL-1 for each benzophenone) were in the range of 86.9-103.3% with relative standard deviations (n = 3) below 9.2%.2. The dummy molecularly imprinted polymers (DMIPs) were prepared by Pickering emulsion polymerization. BPAP, namely 4,4’-(1-phenylethylidene) bisphenol, was selected as dummy template to avoid the leakage of the target bisphenols (BPs). The microsphere particles were characterized by scanning electron microscopy and nitrogen adsorption-desorption measurements, demonstrating that the regular-shaped and medium-sized particles were obtained with a specific surface area (SBET) of 355.759 m2 g-1 and a total pore volume of 0.561 cm3 g-1. The molecular imprinting properties of the particles were evaluated by static adsorption and chromatographic evaluation experiments. The association constant (Ka) and maximum adsorption amount (Qmax) of bisphenol A (BPA) were calculated to be 0.115 mmol L-1 and 3.327 μmol g-1 using Scatchard analysis and good class selectivities of seven BPs were demonstrated by the chromatographic evaluation experiment. The microsphere particles were then used for solid phase extraction (SPE) sorbent for selective extraction of seven BPs. The method of DMIP-SPE coupled with HPLC-DAD was successfully established for the extraction and determination of seven BPs from environmental sediment samples with method detection limits of 0.6-1.1 ng g-1. Good recoveries (75.5-105.2%) for sediment samples at two spiking levels (500 and 250 ng g-1) and reproducibility (RSDs< 7.7%, n=3) were obtained in the experiment procedure.