Preparation Of Solid Phase Microextraction Fiber Based On Covalent Organic Frameworks And Application In The Detection Of Bioamines And Pyrethroids

Covalent Organic framework(COFs)is a kind of porous crystalline materials formed by covalent bonding of small organic monomers.Due to its regular skeleton,large specific surface area,open porous structure,abundant functional groups,good adsorption performance and various design and synthesis schemes,COFs is considered as a highly efficient material for solid-phase Microextraction(SPME)fiber coating.On the one hand,the network structure and aperture of COFs can be controlled by designing organic monomers with different geometric shapes.On the other hand,the introduction of functional groups in COFs can be realized by in situ or post modification methods.COFs with different structures and surface chemical properties have different adsorption capacities for different organic compounds.In this paper,SPME fibers were prepared from two groups of COFs materials.Combined with gas chromatography-mass spectrometry(GC-MS),the analysis method of biogenic amines and pyrethroids was established,and the extraction conditions were optimized.The extraction performance of COFs coated SPME fiber was evaluated,and the interaction mechanism between COFs and target was discussed.Finally,it was applied to the determination of biogenic amines in red wine and pyrethroids in tea.(1)Two kinds of fiber SPME extractors were prepared by coating two kinds of COFs(COF-DL229 and COF-300)with epoxy resin on a fibrous stainless steel substrate.A method for the determination of phenylethylamine and tyramine in water matrix was established by GC-MS.Salt concentration,alkali concentration,derivative test dose,extraction temperature and extraction time were optimized,and the optimal extraction conditions were determined.Compared with commercial SPME fiber,the extraction efficiency of COF-DL229 extractor for 2-phenylethylamine and tyramine is significantly better than that of most commercial fibers,which can reach more than 10 times.Under the optimized SPME conditions,the established method had a wide linear relationship and a low detection limit of 10-1000?g·L^-1 for phenethylamine and tyramine,and the detection limits of phenethylamine and tyramine were 0.01?g·L^-1 and 1?g·L^-1,respectively.The intra-day relative standard deviation was 8.47%?10.04%,and the intra-day relative standard deviation was 11.32%?14.95%.Phenylethylamine and tyramine in real wine samples were determined with standard recovery of 87.32%?116.97%.At the same time,COF-DL229 and COF-300 coated fibers also have excellent extraction effect on phenols,which proves the versatility of COF coated fibers.(2)Two-dimensional imine COFs with similar layered structures,BTT-TPA-COF and BTT-TAB-COF(collectively known as BTT-COFs),were synthesized and coated on fibers as SPME extractors to detect six pyrethroids in aqueous solution.XRD,N₂ adsorption,and other characterization results show that BTT-COFs has higher crystallinity,homogeneity of void and better thermal stability.Firstly,the extraction efficiency of BTT-COFs fibers prepared with different polymer adhesives for pyrethroids was compared,and the epoxy resin with high thermal stability was the best.Then,the extraction temperature,extraction time,analytical temperature and analytical time were optimized,and the di-SPME/GC-MS detection method for pyrethroids was established.Compared with the extraction efficiency of commercial SPME fiber and BTT-COFs coated fiber,the extraction efficiency of BTT-COFs coated fiber is significantly higher than that of commercial fiber,among which the extraction efficiency of BTT-TPA-COF is superior,which can reach 10-30 times of that of commercial fiber.The method of pyrethroid DI-SPME/GC-MS based on BTT-TPA-COF fiber was evaluated.The method had the advantages of low detection limit and good stability.The detection limit was 0.002-0.12 ng·L^-1,and the intra-day relative standard deviation was1.38%?8.38%.The daily relative standard deviation was 4.55%?9.83%.Finally,the method was applied to detect the content of pyrethroids in commercially sold tea.The content of pyrethroids was 0.083-98.2 ng·L^-1,and the recovery was 83.2%?125.83%.