Preparation Of Fluorine-functionalized MOFs/COFs And Its Application In Sample Pretreatment

In the field of chromatographic separation science,magnetic solid phase extraction(MSPE)is a technique in sample preparation.The MSPE process only needs to be separated by an external magnetic field,without the need for tedious operations such as filtration or centrifugation.In recent years,graphene(G),carbon nanotubes(CNTs),molecular imprinting(MIP),metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)and other materials are usually used as adsorbents to adsorb complex trace organics in biological and environmental samples.At present,MOFs/COFs materials have the characteristics of high specific surface area,porous structure,easy functionalization and adjustable pore size,etc.,and have become a popular material in MSPE.However,most of the MOFs/COFs materials are a type of porous materials containing benzene rings,which mainly adsorb analytes through hydrophobic interaction,π-π and the force between hydrogen bonds.In order to obtain better extraction efficiency for analytes,functionalizing the surface of MOFs/COFs is one of the effective strategies.In view of the fact that most of the analytes in biological and environmental samples contain F,N,O and other atomic characteristics,we tried to synthesize a class of magnetic adsorbents with high extraction performance.Fluorine-functionalized MOFs/COFs can increase the hydrophobicity of the material to improve the extraction efficiency and have good affinity for fluoride.Fluorine solid phase extraction is a special solid phase extraction technology,mainly used for selective extraction of fluoride.Therefore,fluorine-functionalized magnetic MOFs/COFs materials have good application prospects in sample preparation.However,it is currently reported that fluorine-functionalized MOFs/COFs are still in the initial stage of sample preparation.Therefore,it is meaningful to study the application of fluorine-functionalized MOFs/COFs in sample preparation.The research content of the thesis was as follows:1.Use magnetic UIO-66(4F)as MSPE adsorbent,combined with high performance liquid chromatography(HPLC)to determine Benzoylurea insecticide(Bus)in environmental water,and detailed Several key factors affecting the performance of MSPE were investigated,including the amount of materials,solution volume,extraction time,solution p H,solution ionic strength,eluent type,and number of reuses.The Bus in the samples were separated and determined by HPLC method.The method has a good linear range between 0.5–10μg/L and a lower detection limit(LODs)of 0.14–0.36μg/L.Magnetic UIO-66(4F)was used to enrich Bus in Lijiang water,and the measured recovery rate was 91.4-125.3%.The results showed that it has great practical application potential as a new type of adsorbent.2.Synthesize magnetic COF-F material by solvothermal method,and determine fluorine-containing pesticide by HPLC.To evaluate the performance of magnetic COF-F in MSPE,pyrethroid insecticides((Flucythrinate(FY),Tau-fluvalinate(T-FL),(Acrinathrin,AC),Bifenthrin(BF))were analytes.This article examines in detail several key factors that affect the performance of MSPE,including material dosage,solution volume,extraction time,solution p H,solution ionic strength,eluent type,and number of reuses.Combined with the MSPE–HPLC analysis method,a method for determining pyrethroid insecticides was established,which showed good linearity in the range of 5–500μg/L.magnetic COF-F material enriches trace pesticides in fruit samples,and the measured recovery rate was 85–107.4%.This shows that as a new type of adsorbent,it has great potential in sample preparation.3.Fluorine affinity COFs was used as magnetic adsorbents to enrich herbicides in actual samples.This article has studied in detail several key factors that affect the performance of MSPE,including the amount of materials,solution volume,extraction time,solution p H,solution ionic strength,eluent type,and number of reuses.In this paper,fluorine affinity magnetic COFs were established as MSPE adsorbents,combined with HPLC–UV detection method,to extract four trace herbicides in tap water.Under the best optimized conditions,good linearity was achieved between 0.5–500μg/L,the relative standard deviation was between 0.3–1.2% and the LODswere below 0.07μg/L.In this paper,by detecting tap water samples,a good recovery rate was obtained between 77.5–106.6%.The results showed that the material has the characteristics of efficient and rapided enrichment of trace analytes in actual samples,and were an ideal adsorbent for sample preparation.