Preparation Of Magnetic Nanocomposites Modified By Supramolecular Host Compounds And Their Application In Environmental Estrogen Detection

Environmental estrogens are the most important category of environmental endocrine disruptors.A large part of the established environmental estrogens are highly toxic substances containing benzene ring structures,such as polychlorinated biphenyls PCB,Pyrethroids(Pyrethroids)and so on.Such compounds are toxic,difficult to decompose,and easy to migrate.They can easily enter animals and plants from the soil,water,air,etc.,and eventually enter the human body through the food chain,which seriously affect human health.Among many sample pretreatment methods,magnetic solid phase extraction is a new and efficient sample pretreatment method,which has the advantages of simple and quick operation,high recovery rate,less use of organic solvents,and recyclable.Magnetic nanocomposite materials are multi-component materials.It is a magnetic matrix material with a nanometer size of1-1000 nm or less,such as Fe₃O₄.It has good thermal stability,excellent magnetic properties,and controllable size and shape.It has the characteristic of easy modification.It is also widely used in sample pretreatment technology.Magnetic nanocomposite adsorbent was prepared by bonded supramolecular host compounds,which was used for the analysis of environmental estrogen.In this thesis,the types and hazards of environmental estrogens,sample preparation methods and analytical methods,were reviewed.The development and application of supramolecular host compounds,and the preparation,modification and application of magnetic nanocomposites,especially the supramolecular host compounds application of modified magnetic nanoparticles,were also introduced.In the study,two novel magnetic nanocomposites based on two types of supramolecular host compounds,were prepared for magnetic solid phase extraction adsorbents,which were applied to the analysis of environmental estrogens in actual samples.The main research was presented as the following three aspects:1.Fe₃O₄ magnetic nanoparticles with appropriate size were prepared by hydrothermal method,which was coated with a layer of SiO₂.Cyclodextrin and chitosan supramolecular host compounds were modified on the surface of Fe₃O₄magnetic nanoparticles by alkyl coupling reagent to prepare two kinds of new magnetic nanocomposites(Fe₃O₄@SiO₂@?-CD,Fe₃O₄@SiO₂@CTS).It was characterized by infrared spectroscopy,X-ray diffraction,transmission electron microscopy,nitrogen adsorption characterization and other means to explore the structure performance of magnetic nanocomposites based on supramolecular host modification.2.Fe₃O₄@SiO₂@?-CD magnetic nanocomposites were used as adsorbents for magnetic solid phase extraction for pyrethroid analysis.GC-MS was used as the detection method.Several important factors affecting the extraction effect were optimized,such as extraction time,desorption time,desorption solvent,p H value,sodium chloride concentration,etc.The results showed that the optimum extraction time and desorption time were 30 min and 15 min respectively.And the desorption solution was methanol.Adjusting the p H value of the solution to 7.0,without adding Na Cl to the extraction solution couuld obtain the best extraction effect.In order to further verify the applicability of the method,five kinds of positive tobacco samples were selected to carry out the recovery experiments.Three pyrethroid pesticide residues of bifenthrin,cyfluthrin and deltamethrin were found in the positive tobacco samples,but fenpropathrin was not detected.In addition,five kinds of negative tobacco samples(including flue-cured tobacco,burley tobacco,oriental tobacco,sun cured tobacco and sun cured tobacco)were also analysized by the method.The recovery of four pyrethroid insecticides was 65.94%-106.65%,and the relative standard deviation(RSD)was 1.04%-12.05%?3.Fe₃O₄@SiO₂@CTS magnetic composite materials were used as magnetic solid phase extraction adsorbents for polychlorinated biphenyls(PCBs)analysis.Gas chromatography-mass spectrometry(GC-MS)was used as the detection method.Several important factors affecting the extraction effect were optimized,such as extraction time,desorption time,desorption solvent,p H value and sodium chloride concentration.The method of magnetic solid phase extraction combined with gas chromatography-mass spectrometry was used to detect polychlorinated biphenyls in environmental water.The experimental results showed that the best extraction condition was that:the extraction time and desorption time were 60 min and 15 min,the desorption solution was n-hexane,the p H value of the solution was 7.0,and the addition of Na Cl concentration to the extraction solution was 25.6%,respectively.Under the condition,the best extraction effect could be obtained.Finally,the method of magnetic solid phase extraction coupled with gas chromatography-mass spectrometry analysis for polychlorinated biphenyls was established.It was used for polychlorinated biphenyls analysis in three environmental water samples from Panlongjiang River,Jinzhihe River and Yueyatan water.It was found that only jinzhihe River existed in PCB-28,the concentration was 0.65?g/L.The recoveries of polychlorinated biphenyls in three kinds of environmental water were calculated.The recoveries of polychlorinated biphenyls ranged from 90.34-106.99%,and the relative standard deviations ranged from 1.42-11.31%.This study provides a strategy for the preparation of environmental estrogens in different media by magnetic solid phase extraction(MSPE)using magnetic nanocomposites modified with supramolecular host compounds.