The Preparation Of Organic-Inorganic Hybrid Molecular Imprinted Monolith And Their Application In Solid Phase Microextraction

The organic-inorganic hybrid molecular imprinted monolith was synthesized by using coupling agent to realize one-step synthesis method, which can effectively overcome the shortages of organic molecular imprinting polymer and inorganic molecular imprinting polymer. Organic-inorganic hybrid molecular imprinted monolith has the advantages in the high stereoselectivity, ease of preparation, low backpressure, high mass transfer rate, and so on. At the same time, this method can avoid many tedious procedures in bulk polymerization which may lead to the destruction of some interaction sites. In this paper, the novel organic-inorganic hybrid molecular imprinted monoliths were used in SPME procedure. The high selective, sensitive and rapid analytical methods for the determination of some environmental pollutants in environmental samples and pesticide residues in food were developed. The main contents of this paper are as follows:(1) Organic-inorganic hybrid molecular imprinted monolith (OHMIM) for the recognition of caffeine were prepared by sol-gel technique and in situ polymerization method. The structure and characteristics of the monolith were evaluated. The synthesis conditions such as the type of inorganic precursor and porogenic solvent, the molar ratios of the monomer and cross-linker, the volume ratio of the inorganic alcoholysate and organic part were optimized. The morphology of the monolith was studied by scanning electron microscopy and fourier transform infrared spectra. The imprinted factor of the monolith for caffeine reached3.02. A simple, rapid and sensitive method for the determination of caffeine in children’s milk using the organic-inorganic hybrid caffeine imprinted polymer monolith microextraction combined with high-performance liquid chromatography-photodiodes array detector (HPLC-PDA) was developed. Several parameters affecting the sample pretreatment were investigated, including the type, flow rate and volume of eluent, the flow rate and volume of sample solution. The assay exhibited a linear dynamic range of8-500μg/L with the correlation coefficient above0.9975. Lower limits of detection (LOD, at s/n=3) was2.7μg/L. (2) OIHMIM, which displays good recognition properties for sulfamethoxazole, was prepared in a micro-pipette tip by in situ polymerization with caffeine as the template, acrylamide as the functional monomer, ethylene dimethacrylate as the cross-linker and the methanol as the porogenic solvent, trimethoxysilane as inorganic precursor. The OIHMIP monolith was used as the absorbent of SPME, and a high selective method for the extraction and determination of sulfamethoxazole in honey was established. Some SPME parameters were investigated and optimized. Good linearity was achieved in the range of0.02-2.20μg/g. Excellent reproducibility was found by intra-and inter-day precisions which meets the request of quantitative analysis.(3) An OIHMIP monolith was synthesized in a micro-pipette tip with ketoprofen as the template, which display good recognition properties for ketoprofen, ibuprofen and naproxen. The morphology of the monolith was studied by scanning electron microscopy and fourier transform infrared spectra. The monolith was applied for the selective extraction of KET, IBU and NAP in water samples. Several parameters were investigated, including the nature and volume of extraction solvent, sample volume and flow rate. A high selective method for the determination of these non-steroidal anti-inflammatory drugs in water samples had been established. Good linearity was achieved in the range of12-270μg/L. The intra-and inter-day precisions yielding the relative standard were satisfied for the quantitative analysis.