Preparation Of Novel Hydrophxdxobic MOF Spme Coatings And Its Application In Analysis Of Organic Pollutants

Water pollution is related to the ecosystem and human health and has become a global concern,and organic pollutants are one of the main causes of environmental water pollution because of their long-distance migration,high toxicity and refractory degradation.The common organic pollutants mainly exist in trace and ultra-trace amounts,and the matrix components of real samples are complex,so it is difficult to analyze and monitor the target pollutants directly by instrument.Effective sample pretreatment could grently improve the sensitivity and accuracy of trace organic pollutants detection.Solid Phase microextraction（SPME）has become the first choice for analytical chemistry scientists because of its simplicity,rapid,sensitivity and environmental friendliness.Adsorbent coating is the key of SPME technology,but the existing commercial coating has many problems,such as high cost,short service life,poor high temperature resistance,fiber fracture and so on.Metal-organic framework（MOF）is expected to be an excellent material for SPME probe coating due to its excellent thermal stability and synthesis diversity.However,its water stability is poor,and a large number of the reported hydrophobic MOFs coatings were used under less water and milder temperature conditions,but rarely applied in extremely hot and humid environment.Additionally,the coatings with high-temperature steam stablility would be beneficial for the HS-SPME of low volatile pollutants.In view of this,a novel hydrophobic MOF-SPME probe was prepared and applied to the determination of trace organic pollutants under high temperature and multi-water conditions.The hydrophobic MOF（NH₂-UIO-66（Zr）-shp）was developed into a novel SPME coating by gluing.It was characterized by water contact angle measurement,XRD,FTIR,TG and SEM.The results showed that the water contact angle of the coating material was 134°;the thermal stability was favorable,and the weight loss of the coating material was still less than 5%when heated to 250℃;the surface of the coating material was irregular but sharp and angular;and the thickness of the coating is about 48μm.Combined with GC-MS,the self-made hydrophobic NH₂-UIO-66（Zr）-shp fiber was applied to the headspace extraction of UV filters and PAHs.The hydrothermal stability and anti-matrix effect of the self-made fiber were evaluated.The results showed that the self-made probe has excellent extraordinary stability towards hot water steam,even after being baked in high temperature steam for 21 h,its extraction performance and crystal structure still remain unchanged.And the fiber has outstanding anti-interference ability.Subsequently,the extraction performance and analysis method of the self-made fiber were investigated,the extraction performance of the self-made fiber for UV filters and PAHs was 2.0-6.2 and 1.4-77.3 times higher than that of the commercial PDMS fiber,respectively.The analytical method possessed satisfying repeatability（UV filters:2.3-6.0%;PAHs:4.4-6.8%,n=6）,wide detection range(UV filters:10-50000 ng·L^-1;PAHs:2-5000 ng·L^-1)and low detection limit(UV filters:0.2-2.1 ng·L^-1;PAHs:0.3-2.3 ng·L^-1).The self-made fiber was suitable applied under high heat and multi-water environment.The hydrophobic MOF-SPME was prepared by a pull-up method for the detection of PFAAs in water with HPLC-MS/MS.Compared with commercial PDMS fiber,the self-made NH₂-UIO-66（Zr）-shp fiber was"faster and better"for the extraction of PFAAs,the equilibrium extraction was achieved in 20 minutes and the extraction performance was 53 times that of the commercial PDMS fiber.The optimum experimental conditions were optimized as follows:extraction time 20 min,desorption time 40 min,salt concentration 5%（W/V）,agitation speed 500 rpm·min^-1.The analytical method possessed wide linear range(0.1-1000 ng·L^-1)and low detection limits(0.011-0.103 ng·L^-1).The recoveries obtained with the spiked water samples were in the range of 80.8–119.5%,which demonstrated the applicability of the self-made fiber for the analysis of real water sample.