Synthesis Of Imine-based Magnetic Covalent Organic Framework Materials And The Application In The Determination Method Of Pesticide Residues In Chinese Herbal Medicines

Traditional Chinese medicine is the oldest and most frequently used medical culture in the world.As the quintessence of our country,it has been accumulated for thousands of years and has made great contributions to world medicine in the process of continuous progress and development.As an important means of traditional Chinese medicine treatment,traditional Chinese medicine provides a valuable material basis for the inheritance and development of traditional Chinese medicine,and its quality and safety are very important.There are many types and quantities of Chinese herbal medicines,of which botanicals account for the highest proportion.In recent years,the demand for traditional Chinese medicine-related products has been increasing.With the large-scale and industrialization of agricultural production of Chinese herbal medicines,many growers use pesticides,plant growth regulators and other chemicals irregularly in the process of planting Chinese herbal medicines in pursuit of yield,resulting in serious problems of pesticide residues in Chinese herbal medicines.Some residual pesticides accumulate in the growth environment of medicinal materials and eventually enter the human body,which not only disturbs the balance of the ecosystem,but also brings huge hidden dangers to human health.Therefore,the development of fast,sensitive and low-cost methods for the detection of pesticide residues in Chinese herbal medicines is of great significance for the quality and safety monitoring,control and standard formulation and improvement of Chinese herbal medicines.Chinese medicinal materials contain complex components,such as polysaccharides,volatile oils,alkaloids and flavonoids.Compounds with different chemical structures and polarities make TCM matrices highly complex.Compared with its matrix,the relatively low concentration of pesticide residues in Chinese herbal medicines and the diversity of physical and chemical properties of pesticides have brought great difficulties to the analysis of pesticide residues in Chinese herbal medicines.Therefore,in the process of pesticide residue detection,sample pretreatment directly or indirectly affects the sensitivity of the detection method and the accuracy of the detection results.Compared with traditional pretreatment methods,magnetic solid phase extraction(MSPE)technology has the advantages of rapidity,convenience,low cost and high accuracy,and has broad application prospects in sample pretreatment.The choice of MSPE adsorbent is a key factor affecting the efficiency of MSPE.Therefore,it is of great significance to develop efficient,convenient and green MSPE adsorbent materials.Compared with other materials,covalent organic frameworks(COFs)have received extensive attention in recent years due to their advantages of large specific surface area,strong adsorption capacity,and stable properties.Combining COFs with magnetic carriers to prepare magnetic COFs materials and use them as MSPE adsorbents has been widely studied and applied in the fields of food,medicine,and environment.Based on this,in this study,two imine-based magnetic COFs were successfully constructed using amine-aldehyde monomers,and the morphologies,particle sizes,functional groups and surface properties were investigated through systematic characterization tests.The adsorption capacity of five fungicides and five herbicides was tested respectively.The adsorption mechanism was preliminarily studied by adsorption kinetic experiments and adsorption isotherm experiments.A detection method for fungicide residues in traditional Chinese medicinal materials based on magnetic COFs was established and methodological validation was carried out,and the practicability and reusability of magnetic COFs materials in the detection of fungicide residues in traditional Chinese medicinal materials were evaluated.In order to improve the adsorption capacity of magnetic COFs materials for triazine herbicides,a functional modification method was used to organically combine graphene oxide(GO)with COFs,and a novel magnetic COFs material with good adsorption to triazine herbicides was successfully prepared.A detection method for triazine herbicides in traditional Chinese medicinal materials based on this material was established and verified,and the practicability and reusability of the material in the detection of triazine herbicides in traditional Chinese medicinal materials were evaluated.