Synthesis Andapplication Of Molecularly Imprinted Hybrid Composite Material For Selective Solid-Phase Extraction Tetracyclines Residues In Food

As the molecularly imprinted organic-inorganic hybrid composite material （MIP-HCM）possesses the advantages of both organic polymers and inorganic ceramics, which combinethe superior thermal stability, high hardness and refractive index, low thermal expansioncoefficient, and wide range of permittivity of ceramics with the tremendous toughness,ductility, process ability, and crack-deflection properties of polymers, a novel MIP-HCM wasdeveloped based on molecular imprinting technique in combination with hybrid compositesynthesis and sol-gel technology for selective solid-phase extraction （SPE） and on-line SPE oftetracyclines residues in food. This thesis consists of four chapters and as follows:Chapter1: The dangers of tetracyclines residues and its detection methods wereintroduced. The application of solid-phase extraction to separate and detect the tetracyclinesresidues, and the progress of hybrid composite materials were reviewed.Chapter2: Molecularly imprinted organic-inorganic hybrid composite material（MIP-HCM） were prepared through sol-gel technology by using doxycycline （DOTC） as thetemplate molecule, methacrylic acid （MAA） as the functional monomer andmethacryloxypropyltrimethoxysilane （KH570） as the cross-linker. The key syntheticconditions were optimized by changing some factors （such as the proportion of organic andinorganic, monomer amount and solvent） to obtain sorbent with the controllable adsorptioncapacity, selectivity, hardness and toughness. The synthesized MIP-HCMs were identified byFourier transform infrared （FTIR）, BET, TGAand molecular recognition specific experiment.Accordingly, the MIP-HCMs were used as a solid-phase extraction （SPE） sorbent for theselective extraction Tetracyclines in food, which show higher recoveries （≧74.7%） and lowerlimits of determination (≦96.10mg kg^-1).Chapter3: The oxytetracycline molecularly imprinted organic-inorganic hybridcomposite material was prepared in accordance with the optimized synthesis condition.According to the Fourier transform infrared （FTIR）, BET, TGA, binding experiment anddynamic adsorption experiment, the MIP-HCM processed controllable adsorption capacity,higher selectivity and well hardness. The MIP-HCM was used as solid-phase extraction sorbent for selectively extracting tetracyclines antibiotics in milk. An enrichment factor of18.8along with a good sample clean-up was obtained under the optimized SPE conditions.The average recoveries of three spiked milk were in the range of81.5-104%with theprecision of1.5-5.0%. The limits of detection and quantitation of the proposed method werein a range of4.8-12.7mg kg^-1and16.0-42.3mg kg^-1, respectively.Chapter4: A novel synthesis method of tetracycline-molecularly imprintedorganic-inorganic hybrid composite material and a new technique of on-line solid-phaseextraction coupled with high performance liquid chromatography were developed fordetermination of tetracyclines residue in egg, milk and milk powder. The conditions of on-lineSPE-HPLC were optimized, such as loading solvent, loading flow rate, washing solution andratio of mobile phase. The average recoveries of tetracyclines antibiotics spiked milk were inthe range of102.9%-87.9%. The limits of detection and quantitation of the proposed methodwere in a range of1.13-0.76mg kg^-1and2.53-3.77mg kg^-1, respectively.