The Preparation Of ?-CD Composite Adsorbents And Application In Supermolecular Extraction

As the natural molecule derived from starch,?-cyclodextrin??-CD?is the cyclic oligomer consisting of 7 glucose units linked by?-1,4 linkages.It has been widely studied in the last few decades because of its specific molecular space structure.Compared with?-and?-CD,?-CD has a larger cavity by approximately 0.6-0.8 nm wide.The central cavity of the molecule is lined with skeletal carbons and ethereal oxygens of the glucose residue with many hydroxyl groups arranged around the outer rim.The?-CD exterior is therefore hydrophilic whereas the central cavity is relatively hydrophobic.As a consequence of these features,?-CD can encapsulate a variety of hydrophobic molecules or parts of molecules inside their cavity through non-covalent interactions to form inclusion complexes of the host-guest type,which results its application in enrichment and separation of organic micro pollutants from soil,atmosphere,water and other environmental samples.Because of its non-toxic character to humans,it has been widely used in medical,biomedical and industrial sectors,as well as in cosmetics and food additives.It also has great prospect in the application of sample pretreatment.In this paper,A-?-CD functional monomer was synthesized with?-CD and acryloyl chloride in an easily controlled condition.Then the?-CD polymer materials was prepared through a simple“one-step”polymerization methods.The prepared adsorption materials were characterized by FI-IR,TGA,SEM,BET and XRD,and they are used as the solid phase extraction materials in the sample pretreatment process.After optimization of the extraction conditions including of eluent type,volume and flow rate,sample volume,flow rate,acidity and ionic strength,a simple,rapid and sensitive method was developed for determination of pesticide residues in rice and vegetable samples were developed.The method is simple,fast,high recovery rate and great sensitivity.The main content of this paper is as follows:?1?An acryloyl?-cyclodextrin?A-?-CD?monolithic column for solid phase microextraction?SPME?and determination of carbofuran and carbaryl by high performance liquid chromatography?HPLC?have been prepared through a“one-step”polymerization method.The synthesis conditions,including the volume of cross-linker,the ratio and volume of mixed porogenic solvent consisted of methanol and N,N-dimethylformamide were optimized.The prepared monolithic column was characterized by thermogravimeteric analysis?TGA?,scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FT-IR?and Brunner-Emmet-Teller?BET?measurement.The eluent type,volume and flow rate,sample volume,flow rate,acidity and ionic strength were optimized,in detail.Under the optimized conditions,a simple,rapid and sensitive SPME-HPLC method was developed for determination of carbofuran and carbaryl in rice samples.The experimental results revealed that this method provided high sensitivity,great extraction recovery and wide linearity range for the analytes.The proposed analysis method provided a convenient and effective pretreatment tool for separation and enrichment of carbofuran and carbaryl from complex samples.?2?An acryloyl?-cyclodextrin-silica hybrid monolithic column has been prepared through a“sol-gel”polymerization method for the first time.The synthesis conditions,including the volume of cross-linker,the ratio and volume of inorganic solution to organic solution were optimized.The prepared monolithic column was characterized by TGA,SEM and FT-IR measurement,and was applied for the SPME of methyl parathion and fenthion.The eluent type,volume and flow rate,sample volume,flow rate,acidity and ionic strength were investigated,in detail.Under the optimized conditions,a simple and sensitive SPME-HPLC method was developed for determination of methyl parathion and fenthion in lettuce samples.?3?Fe₃O₄@SiO₂ microspheres were prepared by sol-gel method,and then magnetic silica colloids with surface modification by?-Methacryloxypropyl trimethoxy silane were synthesized.This composite material was prepared by dispersion polymerization of A-?-CD and EGDMA in the presence of A-?-CD microspheres with the surface containing abundant reactive double bonds.The resultant sorbent material was characterized by FT-IR,TGA,XRD and was applied to separation and concentration of methyl parathion and fenthion in vegetable samples.By optimizing the extraction conditions including The eluent type,volume,acidity and ionic strength,high sensitivity analytical method for the determination of methyl parathion and fenthion in vegetables had been developed.