Preparation And Application Of Bisphenol A Molecularly Imprinted Composites On The Surface Of Magnetic Organic Framework

Bisphenol A（BPA）is an important industrial raw material and a typical environmental estrogen.With the extensive use of its products,the pollution problem of BPA is increasingly serious,and thus the risk to human health from long-term exposure can not be underestimated.In this paper,two kinds of BPA molecularly imprinted functional materials were prepared by surface molecularly imprinted sol-gel technology with BPA as template molecule,magnetic zeolite imidazolidate matrix material（MZIF-8）and magnetic covalent organic framework material（MCOFs）as supporting carrier respectively.The details are as follows.（1）MZIF-8,a magnetic zeolite imidazolate matrix material synthesized at room temperature,was used as the carrier,reusable magnetic MOF molecularly imprinted nanocomposites（MZIF-8@MIP）were prepared by layer-by-layer coating process.This method combines the high selectivity of molecular imprinting technology with the high absorbability of MOFs material and the unique separation advantages of magnetic materials.The structure,morphology and properties of the composites were characterized and analyzed.With this composite material as adsorbent,a simple,efficient and highly selective magnetic solid-phase extraction process was developed.A highly sensitive and selective method for the detection of BPA in food was established by using the fluorescence characteristics of BPA and the high-performance liquid chromatography-fluorescence detector.The results showed that MZIF-8@MIP had a good adsorption selectivity and a fast adsorption rate for BPA,and could be collected and reused rapidly.The recovery rate remained above 88.0%after repeated use for 5 times.The linear range of the method is 0.5μg L^-1-5000μg L^-1,the minimum detection limit（LOD）is 0.1μg L^-1（S/N=3）,at the addition level of 0.5μg L^-1、1.0μg L^-1、10μg L^-1,the recovery rate is 88.0%-92.1%,and the relative deviation（RSD）is 1.89%-3.58%.The method was applied to the determination of BPA in tap water,bottled water,lemon juice,canned juice and mineral water.BPA was found in tap water and bottled water,its contents were 7.5μg L^-1 and 1.2μg L^-1,respectively.（2）MCOFs,a magnetic covalent organic frame material with core-shell structure rapidly synthesized at room temperature,was used as the carrier,and carbon dots（CDs）was used as the fluorescence signal material,a magnetic molecularly imprinted composite fluorescent probe（MCOFs@CDs@MIP）was prepared.This method combines the high selectivity of molecular imprinting technology,the high sensitivity of fluorescent materials,the large specific surface area characteristics of covalent organic frame materials and the unique separation advantages of magnetic materials.The structure,morphology and properties of MCOFs@CDs@MIP were characterized and analyzed.Based on the fluorescence quenching phenomenon of probe,a new simple,fast and highly selective method for the detection of BPA fluorescence sensor was developed.The linear range of the method is 25μg L^-1-3000μg L^-1,the minimum detection limit（LOD）is 12μg L^-1（S/N=3）,the recovery rate is86.9%-102.0%,and the relative deviation（RSD）is 2.3%-4.7%.The method was applied to the determination of BPA in canned fruits,canned luncheon meats,milk and beverages,and BPA was detected in all the samples.