Preparation And Application Of Molecularly Imprinted Monolithic Columns Hybridized By Modified Carbon Nanomaterials

Life is getting better and better,but the trouble is no less,food safety is one of the problems that bother people.The monitoring of food safety should be implemented with the help of effective detection methods,sample preparation is essential in food analysis.Molecular imprinting technology is often applied to food analysis with its outstanding advantages.Traditional molecularly imprinted polymers have the disadvantages of low adsorption capacity,poor selectivity and leakage of templates.In view of this,several MIP monolithic columns have been developed modified by modified nanomaterials to improve the efficiency of sample pretreatment.Adsorption performance and selectivity of the monolithic column were investigated by breakthrough curves and recovery tests.The characterization of the monolithic column was performed by scanning electron microscope,infrared spectrometer and other instruments.Finally,the application value of the column in the food analysis was verified.The main contents of this paper are as follows:1.Introduction:A brief overview of sample pretreatment techniques,including liquid extraction,solid phase extraction and solid phase microextraction,was briefly reviewed.The principle and development of molecular imprinting technology,as well as the common polymerization methods and characterization methods of MIP were introduced,and then the development of molecular imprinting solid phase extraction?MISPE?was introduced.MISPE was often used for sample preparation because of its unique advantages.This chapter described the application of MISPE in food analysis,including analysis of mycotoxins,analysis of veterinary drug residues and pesticide residues.For the lack of MISPE,this chapter also made a detailed summary.Because of its special properties,nanomaterials are often used to modify MIP.This chapter introduced the characteristics and modification methods of nanomaterials,as well as the application in MIP.Finally,based on the application status of MISPE,it was proposed to modify MIP with nanomaterials for food analysis.The content of this paper was briefly summarized and the research significance was indicated.2.Preparation of molecularly imprinted monolithic column doped with carbon quantum dots and its application in the detection of aflatoxin B₁?AFB₁?:The study in this chapter using 5,7-dimethoxycoumarin as alternate template for AFB₁,and methacrylic acid?MAA?as functional monomer,ethylene glycol dimethacrylate?EDMA?as cross-linker,azobisisobutyronitrile?AIBN?as initiator,dummy molecularly imprinted monolithic columns doped with carbon quantum dots?CDs??CDs-DMIP?were prepared by heat-initiated in-situ polymerization.The column capacity,recovery,precision,enrichment factor and other performance evaluation indexes of the column were examined experimentally.The morphology and structure of the column were characterized by scanning electron microscopy?SEM?and Fourier transform-infrared spectroscopy?FT-IR?.Finally,the impurity removal and adsorption effects of the monolithic column were investigated by high-performance liquid chromatography-fluorescence detection?HPLC-FLD?,experiments showed that CDs-DMIP monolithic columns have high specificity for the target AFB₁,and the imprinting factor was 4.9.The column was first used for the extraction of AFB₁ in peanuts and enrichment factor was as high as 71times with good impurity removal effect.The detection limit of this method was 0.118 ng mL^-1,it can be used for trace analysis of AFB₁ in peanuts.3.Novel coordination polymer imprinted monolithic column for solid phase extraction of flumequin?FLU?in fish:The column was synthesized using FLU-Zn²⁺as template,itaconic acid and 4-vinylpyridine as bifunctional monomers,EDMA as cross-linker,AIBN as initiator,silanized graphene?SGO?as modification material.The synthesis conditions of the column were optimized by the response surface methodology.The column was characterized by SEM and FT-IR,and the adsorption performance was investigated by breakthrough curves.The impurity removal and adsorption effects of the column were investigated by HPLC-FLD,results showed that SGO-CIP columns have high specificity for the target FLU and was first applied to the extraction of FLU from fish,recovery reached 95.2%,the enrichment factor was over 40-fold,and the impurity removal effect was good.The detection limit of this method was as low as 1.58 ng mL^-1,it can be applied to trace analysis of FLU in fish.4.Development and application of molecularly imprinted monolithic column based on functionalized?-cyclodextrin:Using synthetic silylated multi-walled carbon nanotubes as modifying materials and thiabendazole as template,acryl-?-cyclodextrin and MAA are bifunctional monomers,EDMA as cross-linker and AIBN as initiator,molecularly imprinted monolithic column was polymerized in capillary by in-situ polymerization in a mixed porogen toluene-methanol-n-dodecanol?1:0.5:1.5,v/v/v?.The synthesis conditions of the columns were optimized by the response surface method,and the adsorption properties of different types of columns were investigated by breakthrough curves.The impurity removal and adsorption effects of the column were investigated by HPLC-FLD.The method could simultaneously detect thiabendazole,carbendazim and fuberidazole in citrus and the recovery was greater than 84.9%.Results showed that the column has strong specificity,good adsorption effect and large enrichment factor,and can be used for the detection of benzimidazole residues in fruit.