Rapid Preparation And Application Of ZIF-8 Materials As SPME Coating

Polycyclic aromatic hydrocarbons(PAHs)are widely distributed in the environment due to their high fluidity,toxicity,carcinogenicity and teratogenicity.However,due to their low content in environmental water samples and complex sample matrix,they need to be pretreated.Solid phase microextraction is a sample pretreatment technology integrating sampling,extraction,concentration and injection.It is widely used in the analysis and detection of pollutants in the environment.Metal organic framework materials are used in the field of solid phase microextraction coatings because of their high specific surface area,high porosity and adjustable structure.In this paper,a relatively simple,rapid and stable method was studied to prepare Zeolite imidazole ester skeleton structure material ZIF-8 coating as solid-phase microextraction(SPME)fiber,and combined with gas chromatography to realize the enrichment and analysis of common polycyclic aromatic hydrocarbons in environmental water samples.The main contents are as follows:1.Firstly,dopamine was modified by self polymerization on stainless steel wire with higher mechanical strength,and the formed polydopamine was used as molecular linker to improve fiber durability.Then,ZIF-8 coating was prepared by electrochemical deposition method with the advantages of mild preparation conditions,low preparation cost and simple operation,solid phase microextraction fiber with appropriate thickness of ZIF-8 coating was obtained by controlling deposition voltage and deposition time,eight polycyclic aromatic hydrocarbons were extracted,the effects of zinc salt type,deposition voltage and deposition time on the extraction properties of the prepared coatings were investigated,and characterized by SEM,FT-IR,XRD and TG,the main factors affecting the extraction efficiency,such as extraction temperature,extraction time,ionic strength and desorption time,were optimized.Under the optimal conditions,the detection linear range of the target analyte is 0.05-50 μg/L,the linear correlation coefficient is in the range of 0.9928-0.9998,and the detection limit is 0.010-0.054 μg/L,which is used for the detection of actual samples,and the recovery is between 80.1%-1 13.8%.2.Firstly,the prepared milk like viscous liquid layered hydroxyl double salt is prepared on the thoroughly cleaned stainless steel wire by electrochemical deposition method as an intermediate,and then it is placed in the prepared methanol solution of 2-methylimidazole and triethylamine.The strong anion exchange of hydroxyl double salt can make the imidazole ion in the solution replace the anion in the coating and successfully combine with zinc ion,It was transformed into ZIF-8 coating in situ and treated with ionic liquid and neutral silicone sealant as solid phase microextraction fiber.The coated fiber was used to extract 8 polycyclic aromatic hydrocarbons in environmental water samples,and its preparation and extraction conditions were optimized.Under the optimum conditions,a online analysis method is established with wide linear range(0.05-100 μg/L),low detection limit(0.007-0.059 μg/L)and high enrichment multiple(3414-25763),and has been successfully applied to the detection and analysis of polycyclic aromatic hydrocarbons in actual water samples,and the recovery is 80.1%-121.4%and the relative standard deviation is in the range of 1.8%-9.8%.