Preparation Of Restricted Access Media-Surface Molecularly Imprinted Materials And Application Research In The Real Samples

The restricted access medium-molecularly imprinted polymer composite material can not only selectively recognize target small molecules but also exclude the interference of macromolecular proteins,improve the selectivity and adsorption performance of adsorbents,and are widely used in food,environment and other fields.In this paper,monodisperse crosslinked polyglycidyl methacrylate-polyethylene glycol dimethacrylate(P_GMA/EDMA)microspheres and nano-core shell silica were used as carriers,17β-estradiol and norfloxacin,ciprofloxacin as a template molecule,using reversible addition fragmentation chain transfer polymerization（RAFT）or surface-initiated atom transfer radical polymerization（SI-ATRP）technology to prepare three new restricted access media-molecularly imprinted polymer（RAM-MIP）material.And RAM-MIP were used different extraction techniques and combined with high performance liquid chromatography to analyze and detect hormones or antibiotics in actual samples such as milk and lake water.1.Preparation of monodisperse restricted-access surface molecularly imprinted polymers and selective extraction of 17β-estradiol from milkUsing 4-5μm monodisperse P_GMA/EDMA microspheres as matrix,acryloyl chloride modifiedβ-cyclodextrin as hydrophilic functional monomer,17β-estradiol（17β-E2）as template molecule,using RAFT polymerization technology successfully prepared a new type of highly hydrophilic restricted-access molecularly imprinted polymer 17β-E₂-RAM-MIP with a protein exclusion rate of 98.6%.At the same time,the materials have good monodispersity,efficient binding capacity,fast mass transfer rate and good selectivity.A pretreatment process using 17β-E₂-RAM-MIP as dispersive solid phase extraction（DSPE）adsorbent was established and combined with RP-HPLC to separate and detect 17β-E₂ in milk samples.The result showed that the recovery rate of 17β-E₂is 88-95%,the relative standard deviation（RSD）is less than 4%,and the limit of detection（LOD）and limit of quantification（LOQ）of this method are 2.08 and 9.29.2.Preparation and performance research of norfloxacin restricted access molecularly imprinted polymers by SI-ATRP technologyNano-scale core-shell silica microspheres were prepared by the"one-pot method"reaction,then acidified to make the surface rich in hydroxyl groups,and the surface of the core-shell silica was modified with 2-bromoisobutyryl bromide to prepare a macroinitiator.Using methacrylic acid as the functional monomer and norfloxacin（NOR）as the template molecule,a novel restricted-access molecularly imprinted polymer was successfully prepared using SI-ATRP technology.A pretreatment process with NOR-RAM-MIP as solid phase extraction adsorbent was established,and the content of NOR in lake water samples was detected by HPLC-UV.The results showed that the intra-day recovery and RSD of NOR at three different concentrations were 90.8-98.6%and 3.2-5.5%,while the inter-day recovery and RSD are 89.5-99.2%and 3.9-5.8%.The LOD and LOQ of NOR were measured at signal-to-noise ratios of 3 and 10,respectively,which were 2.67 and 8.84μg·L^-1.3.Preparation and performance research of ciprofloxacin restricted access molecularly imprinted polymers by bifunctional monomer methodUsing nano-core-shell silica as a carrier,the surface is modified with the silane coupling agent 3-（trimethoxysilyl）propyl-2-methyl-2-acrylate（MPS）,and trifluoromethacrylic acid（TFMAA）and 4-vinylpyridine（4-VP）as bifunctional monomers,and ciprofloxacin（CIP）is used as a template molecule to prepare a surface restriction medium-ciprofloxacin molecularly imprinted polymer.The CIP-RAM-MISPE pretreatment method was used to separate and enrich ciprofloxacin from the spiked milk beverage samples.The LOD and LOQ of CIP are 2.05 and 7.98μg·L^-1,respectively.The intra-day extraction recovery rate and intra-day precision RSD of CIP at three different concentrations(100,200 and 300μg·L^-1)were between 91.6-97.9%and 3.8-4.5%,respectively.The inter-day recovery rate and RSD were between 90.1-98.8%and 3.5-5.2%.