| The issues of food safety and environment protection emerge as focal points in recent years.With the development of agriculture,pesticides and veterinary drugs have been used widely.These chemicals have endangered the ecological environment and human health,Estradiol,malathion,heptachlor and endosulfan were even classified as the environmental endocrine disrupting chemicals?EDCs?.EDCs refer to a diverse range of synthetic and natural xenobiotic that interfere with the synthesis,secretion,transport,binding action,or elimination of natural hormones in the body,which could make the reproductive organs,reproductive function and reproductive behaviors abnormal,resulting in fertility descending,reproduction function damage,community quantity decrease and eventually leading to species extinction.Owning to the low concentration of EDCs in enviromental media or food matrix,a suitable residue determination method with high selevtivity and sensitivity is highly desirable.Molecularly imprinted polymers?MIPs?are tailor-made ones with the shape and the spatial arrangements of the functional groups are complementary to the structure of the template.Owing to their desired promising characteristics,such as physical robustness,thermal stability,excellent reusability,low cost and easy preparation,MIPs have aroused extensive attention and been widely used.Therefore,the environmental protection and food safety will be promising fields for the application of MIPs.The thesis mainly presents the research on preparation of different kinds of MIPs based on different polymerization methods?bulk polymerization method,precipitation polymerization method and surface imprinted polymerization method?,the recognization mechanism was studied by means of molecular simulation,ultravoilet spectra?UV?and 1H-nuclear magnetic resonance?1H NMR?,the structrue characterization and adsorption performance were evaluated with multitudes of analytical method.Finally,MIPs were packed into MIP-SPE cartridge and applied in the determination of residues in real samples.1.Preparation,characterization and application of estradiol MIPsThe MIPs were prepared,optimized with orthogonal design L36?34?,by bulk polymerization method with 17?-estradiol as a template,2-?methacryloyloxy?ethyl phosphate?MEP?as a functional monomer,trimethylolpropane trimethacrylate?TRIM?as a crosslinker,azodiisobutyronitrile?AIBN?as an initiator,and acetonitrile-toluene?3:1,v/v?as a porogen.The molecular recognization mechanisms of estradiol and MEP were evaluated by molecular simulation,UV and 1H NMR.MEP interacts specifically with 17?-estradiol by hydrogen bond with the ratio of 2:1.The MIPs exhibit a high affinity,recognition specificity and efficient adsorption performance for 17?-estradiol.Scanning electron microscope?SEM?,Fourier transform infrared spectroscopy?FT-IR?,surface area and porosimeter analyzer,thermogravimetric/differential thermal analyzer?TG/DTA?and Particle size analyzer were used to characterize the properties of MIPs.The adsorption properties were evaluated with kinetic adsorption,adsorption isotherms,adsorption selectivity and adsorption repeatability.The estradiol residues in pork,chicken and eel were cleaned up with MIP-SPE and determinated by GC-MS/MS.The results showed that the quantitative limits of pork,chicken and eel were 1?g kg-1,when spiked with 1?g kg-1?10?g kg-1,the recoveries of pork,eel and chicken were 76.54%?116.83%?with RSD being 5.2%?9.g%?,77.72%?111.06%?RSD,3.8%?13.3%?and 70.80%?112.39%?RSD,1.8%?14.7%?,respectively.2.Preparation,characterization and application of malathion MIPs with precipitation polymerization methodThe MIPs were prepared using precipitation polymerization method with malathion as a template,Methacrylic acid?MAA?as a functional monomer,Etylene glycoldimethacrylate?EGDMA?as a crosslinker,Azo-bisisobutyronitrile?AIBN?as an initiator,and acetonitrile-chloroform?1:1,v/v?as a porogen.The molecular recognization mechanisms of malathion and MAA were evaluated by molecular simulation,UV and 1H NMR.MAA interacts specifically with malathion by hydrogen bond with a ratio of 2:1.FT-IR,SEM,TG/DTA,surface area and porosimeter analyzer,and particle size analyzer were used to characterize the properties of MIPs.The adsorption properties were evaluated with kinetic adsorption,adsorption isotherms,adsorption selectivity and adsorption repeatability,which shows that MIPs exhibit high affinity,recognition specificity and efficient adsorption performance for malathion.The malathion residues in soil,tap water and plant were cleaned up by MIP-SPE,determined by GC-FPD and confirmed by GC-MS/MS.The quantitative limits of tap water,soil and cabbage were 0.001 mg L-1,0.004 mg kg-1 and 0.004 mg kg-1 respectively.The spiked recoveries of malathion in tap water,soil and cabbage were 96.06%?111.49%?with RSD being 5.7%?9.2%?,98.13%?103.83%?RSD,3.5%?8.7%?and 84.94%?93.69%?RSD,4.7%?5.8%?,respectively.3.Preparation,characterization and application of malathion surface MIPs with nano-TiO2 as core using sol-gel polymerization method.The surface MIPs were prepared with sol-gel method using malathion as a template molecule,?3-aminopropyl?triethoxysilane?APTES?as a functional monomer,tetraethyl orthosilicate?TEOS?as a crosslinker,TiO2 nanowire?TiO2 NW?as a support.The molecular recognization mechanisms of malathion and APTES were evaluated by molecular simulation,UV and 1H NMR.APTES interacts specifically with malathion by hydrogen bond with a ratio of 2:1.FT-IR,SEM,transmission electron microscopy?TEM?,X-ray diffraction?XRD?,energy dispersive X-ray spectroscopy?EDX?,electron diffraction?ED?,TG/DTA,elemental analyzer,surface area and porosimeter analyzer and particle size analyzer were used to describe the characterization of MIPs.The adsorption properties were evaluated with kinetic adsorption,adsorption isotherms,adsorption selectivity and adsorption repeatability,which show that MIPs exhibit a high affinity,recognition specificity and efficient adsorption performance for malathion.The malathion and maloxon residues in water were cleaned up by MIP-SPE,determined by GC-FPD and confirmed by GC-MS/MS.The quantitative limits of malathion and maloxon in water were both 0.005 mg L-1.When spiked at 0.01 mg L-1?0.1 mg L-1,The spiked recoveries of malathion and malaoxon in tap water were 60.55%-85.35%?with RSD being 4.2%-6.5%?and 75.75%?108.41%?RSD,7.0%?7.7%?,respectively.4.Study on and application of conventional method and MIP-SPE method in the determination of heptachor and endosulfan residues in porkTwo methods for determinaton of heptachor and its metabolites,endosulfan and its main metabolite residues in pork were established.In the first method,the pork samples were extracted with acetone-n-hexane,then cleaned-up by gel permeation chromatography?GPC?and florisil solid phase extraction?SPE?cartridge.The extracts were determined by gas chromatography equipped with electron capture detector?GC-ECD?,followed by validation using gas chromatography-mass spectrometry?GC-MS?with negative chemical ionization?NCI?.At spiked concentrations of 0.01 mg kg-1?0.1 mg kg-1,The spiked recoveries of heptachlor,heptachlor-endo-epoxide and heptachlor-exo-epoxide in pork were 82.0%?106.1%?with RSD being 4.7%?8.1%?and 80.1%?101.5%?RSD,4.7%?8.8%?,81.1%?108.5%?RSD,4.0%?11.3%?,respectively.The limit of quantification for each analyte were 0.01 mg kg-1,which satisfied the current maximum residue limit permitted in pork.Instead,MIP-SPE cleanup were used as cleanup procedure in the second method.Combined with the restricted access materials?RAM?and the dummy MIT,the RAM-MIPs with hydrophilic external layer were prepared using endosulfan as a template,MAA as a functional monomer,glycidilmethacrylate?GMA?as a pro-hydrophilic co-monomer,EGDMA as a crosslinker,AIBN as an initiator,and toluene as a porogen.FT-IR,SEM,TG/DTA,surface area and porosimeter analyzer,and particle size analyzer were used to characterize the properties of MIPs.The quantitative limits of each compounds were 0.005 mg.kg-1.At spiked concentrations were 0.005 mg.kg-1?0.05 mg.kg-1,the spiked recoveries of heptachor and its metabolites in pork were 58.13%-79.77%?with RSD being 2.0%?15.9%?,endosulfan and its main metabolite in pork were 50.96%?107.73%?RSD,1.4%?14.3%?,respectively.the quantitative limits for each analyte was 0.005 mg kg-1.Compared with the cleanup precedure of GPC and florisil solid phase extraction,the MIP-SPE has more advatage in the determination of residues in pork,such as low cost,excellent clean-up performance,relieve labour intensity,shorten cleanup time.In addition,it can be applied in simultaneously determination of the residues of heptachlor and its metabolite and endosulfan and its metabolites in pork. |
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