The Preparation Of Zearalenone Molecular Imprinting Polymers And Its Characterization And Solid-phase Extraction Application

Zearalenone（ZEN）is a mycotoxin of great concern in the storage,distribution and consumption of foodstuffs because it is highly toxic and harmful.Extraction,purification and detection of ZEN in grain and oil foods are extremely important aspects of contamination prevention and control.Currently,the development of efficient,accurate and green pretreatment methods to effectively exclude coexisting interferents in food matrices and achieve efficient and accurate detection of ZEN has become a hot research topic.In this study,mesoporous silica（MS）was prepared from rice husk,a by-product of rice processing,and used as a carrier for molecular imprinting on the surface to prepare molecularly imprinted polymers（MS@MIPs）;the adsorption kinetics,thermodynamics and specificity of MS@MIPs for ZEN were investigated,and a solid phase extraction（MI-SPE）column was prepared using MS and MS@MIPs and coupled with high performance liquid chromatography（HPLC）for the determination of ZEN in maize samples.The main results of the study are as follows:Fristly,preparation and characterization of MS@MIPs.The MS@MIPs were prepared by soft template method,and the highest yield of MS@MIPs was obtained at a stirring speed of700 r·min^-1 and a concentration of 0.02 mol·L^-1 of cetyltrimethylamine bromide（CTAB）,with ideal crystal structure and uniform pore size and distribution.The MS@MIPs were prepared by precipitation polymerization method,with quercetin（QUE）as the alternative template,methacrylic acid（MAA）as the functional monomer and methanol as the reaction solvent,and the ratio of functional monomer to template molecules（QUE:MAA）was 1:4.The results of nitrogen adsorption experiments showed that both MS and MS@MIPs were typical mesoporous materials,but the total pore volume and specific surface area of MS@MIPs(0.2038 cm^-1)were higher than those of the MS@MIPs.surface area(0.2038 cm³·g^-1,311.9737 m²·g^-1)was much smaller than that of MS(0.8106 cm³·g^-1,876.2042 m²·g^-1),indicating that molecular imprinting occurred both on the surface and in the pores of MS;scanning electron microscopy（SEM）and transmission electron microscopy（TEM）observed that both MS and MS@MIPs were spherical structures,the and the molecularly imprinted polymer layers masked the regular mesoporous structure of MS.In addition,the successful occurrence of molecular imprinting behavior was further confirmed by the use of X-ray photoelectron spectroscopy（XPS）and Fourier infrared spectroscopy（FTIR）.Secondly,the study of the adsorption behavior of MS@MIPs.Molecular imprinting conferred excellent adsorption ability to MS@MIPs.When the initial concentration of ZEN was 50μg·m L^-1,MS@MIPs was added at 10 mg,p H 7.0,and temperature 30°C,the adsorption of ZEN by MS@MIPs reached equilibrium at 60 min,and the adsorption amount was as high as 10.98μg·mg^-1 at that time,which was much larger than that of MS under the same conditions(0.64μg·mg^-1).The quasi-secondary kinetic model was able to simulate the adsorption process of MS@MIPs on ZEN well（R²=0.999）;compared with the Freundlich model,the Langmuir model had a better fit to the adsorption isotherms of MS@MIPs with R²ranging from 0.978～0.995;further,by fitting the Scatchard model and The thermodynamic parameters were calculated,and it was hypothesized that MS@MIPs might specifically sequester ZEN through three to four hydrogen bonding sites,and thus exhibited overall single-molecule adsorption close to the chemotactic force(ΔH=61.24 k J·mol^-1),which was spontaneous（ΔG<0）,heat-absorbing（ΔH>0）,and underwent three stages of rapid,slow and internal diffusion.In addition,the imprinting factor of MS@MIPs on ZEN was 5.78 in the mixed-label solution of four mycotoxins,confirming the excellent affinity and selectivity of MS@MIPs on ZEN.Finally,preparation and application of MI-SPE.The composition of the sorbent of MI-SPE was optimized,and the highest recovery of ZEN was achieved at about96.00%when the MS@MIPs:MS（m/m）was 80:20.The optimal elution conditions for MI-SPE were:acetonitrile:water=9:1,and the amount of eluent was 3 m L;when the concentration of ZEN in the upper sample solution was 10μg·m L^-1 and the solution p H 7.0,the recovery of MI-The extraction recovery of ZEN by SPE reached 95.16%when the concentration of ZEN in the upper sample solution was 10μg·m L^-1 and the solution p H 7.0.In addition,the extraction recovery of ZEN by MI-SPE was maintained at 84.79%at the 7th reuse,indicating the high practical and economic value of MI-SPE.When MI-SPE was coupled with HPLC（MI-SPE-HPLC）for the determination of ZEN in mixed-label corn solutions,corn samples with 5～100μg·kg^-1 ZEN spiked could be detected by the MI-SPE-HPLC method,and the linearity law was satisfied,meeting the requirements of the current national standards for the detection limit and quantification limit of ZEN.It can be seen that the method has good precision and high confidence,and has a promising application.