Preparation Of Restricted Access Media-Magnetic Molecularly Imprinted Materials And Application In The Analysis Of Biological Samples

Restricted access media-magnetic molecularly imprinted polymers?RAM-MMIPs?can not only effectively block macromolecular materials,but also identify small molecular target materials.And it has the advantages of good adsorption speed,high adsorption capacity,large selectivity,good hydrophilicity,easy to replace,long replacement,simple operation,green,environmental protection and so on.It is widely used in chromatographic separation,food,biomedical and other fields.In this study,monodisperse crosslinked magnetic poly?4-chloromethyl-styrene?(Fe₃O₄@P_VBC-_DVB),magnetic poly?propylene methacrylate?(Fe₃O₄@P_GMA-_EGDMA)and magnetic silica?Fe₃O₄@SiO₂?microspheres were used as solid-phase substrates,respectively.Surface-initiated atom transfer radical polymerization?SI-ATRP?or reversible-addition fragmentation chain transfer polymerization?RAFT?technology can be used to prepare untreated biological samples directly,quickly,selectively separate and enrich three RAM-MMIPs for enrichment of target analytes,and establish a magnetic solid-phase extraction-high performance liquid chromatography?MSPE-HPLC/UV?analysis to detect tetracyclines in biological samples Method for residues of antibiotics?TCs?,melamine type additives and imidazolinone herbicides.1.Preparation of RAM-MMIPs microspheres for selective enrichment of tetracycline veterinary drugsUsing 5-6?m monodisperse Fe₃O₄@P_VBC-DVBBC-DVB microspheres as solid matrix,tetracycline as template molecule,methacrylic acid and ethylene glycol dimethacrylate,egg samples which can be directly untreated were prepared by SI-ATRP.Moreover,RAM-MMIPs materials with TCs can be enriched rapidly and efficiently.The morphology of the material was characterized in detail by FTIR,SEM,TEM,VSM,TGA and other analytical methods.The total thickness of the imprinted layer and hydrophilic polymer layer was about 600 nm.The protein exclusion experiment showed that the protein exclusion rate of the material was 99.4%.The results showed that the adsorption performance of the material was more in line with the two-stage kinetic model?Blanchard?and Langmuir isothermal model,and had good specific adsorption.Then,it was used as MSPE adsorption material,and its adsorption and desorption conditions were optimized in detail.Finally,MSPE-HPLC/UV analysis method for the determination of tetracycline antibiotics residues in egg samples was established.In the established method,the linear relationship of TCs concentration in the range of 5.0-700?g/L is good,the detection limit?LOD?is 2.21-2.67?g/L,which calculated by 3?S/N?.The LOD is lower than the maximum residue limits of TCs in eggs of 200?g/L,200?g/L and 400?g/L stipulated by relevant departments of China,the European Union and the United States.The recovery was 84.2-98.5%and RSD are 1.7-5.9%.2.Preparation and identification of a novel superparamagnetic core-shell compositeA novel Melamine?MA?-composite RAM-MMIPs was successfully synthesized on the surface of 5.5-6?m monodisperse Fe₃O₄@P_GMA-_EGDMAGDMA microspheres by SI-ATRP technology.By characterizing its topographical features,the total thickness of the imprinted layer and the hydrophilic polymer layer of the material is about 583 nm.Then,it was used as MSPE adsorption material,and its adsorption and desorption conditions?adsorbent dosage,pH value of sample solution,ultrasonic adsorption time,selection of eluting solvent?were optimized in detail.Finally,MSPE-HPLC/UV enrichment and analysis method of melamine trace residues in milk samples was established.The LOD?10.30?g/L?is lower than the maximum residue limit of MA in milk of 150?g/L stipulated by the United Nations.The results showed that the RSD of MA was87.1-106.5%and 2.1-5.1%,while the RSD of MA was 87.5-105.3%and 1.6-4.8%,respectively.3.Preparation and application of imazethapyr-restricted access media-magnetic molecularly imprinted nanomaterialsA new superparamagnetic core-shell nanomaterial was prepared on the surface of Fe₃O₄@SiO₂ by RAFT with superparamagnetic Fe₃O₄ as the core,imazethapyr?IM?as the template molecule.The results show that the total thickness of imprinted layer and hydrophilic polymer layer is about 63 nm.In the application of the developed method,the linear relationship between the concentration of imidazolinone nicotinic acid in the range of 5-100?g/L is good?0.9993,?,the LOD is 2.13?g/L and the LOD is far lower than the maximum residue limit of imidazolinone herbicide in beef and other by-products stipulated by the United States,which is 100?g/L.The RSD of imazethapyr was 86.9-103.2%and2.5-6.4%,while the RSD of daytime and daytime were 87.3-102.5%and 2.6-5.9%,respectively.In summary,the method developed in this study is simple and efficient,and can be used to directly enrich and analyze imidazolinone herbicide target analytes from protein containing milk biological samples.