Study On The Fabrication Of Fluorophilicity-Based Multiple Monolithic Fibers And Its Application In The Monitoring Of Perfluorinated Alkyl Substances

Perfluorinated alkyl substances(PFASs)are a new type of persistent organic pollutants.It is of great practical significance to develop a highly sensitive,reliable and accurate detection method for PFASs.In this study,accordting to the chemical properties and molecular structures of PFASs,suitable fluorinated functional monomers and other auxiliary monomers were screened to fabricate highly fluorinated monoliths which were utilized as the adsorbents of multiple monolithic fiber solid phase microextraction(MMF-SPME).At the same time,the introduced MMF-SPME was combined with HPLC-MS/MS to develop highly sensitive method for the determination of ultra-trace PFASs in environment,biology and food samples.The main results are as follows:(1)A highly fluorinated multiple monolithic fiber(DAVC/MMF)was synthesized by using 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate as fluorinated monomer and vinylbenzyl trimethyl ammonium chloride as auxiliary monomer.In order to achieve the expected extraction performance,the effects of preparation conditions(including ratios of monomers to cross-linkers,monomer mixture to porogenic solvent)and extraction parameters(including desorption solvent,adsorption and desorption time,pH value and ionic strength in sample matrix)were systematically investigated.The results showed that DAVC/MMF could effectively extract perfluorocarboxylic acids by fluorophilic and anion exchange interactions.Under the optimum conditions,the developed DAVC/MMF-SPME-HPLC-MS/MS method was applied to quantify ultra-trace perfluorocarboxylic acids in environmental water and milk samples.The limit of detection(LOD,S/N=3)and limit of quantification(LOQ,S/N=10)values of the method were 0.40-4.40 ng/L and 1.32-14.5 ng/L in water sample,respectively.The related values in milk sample were 0.90-12.1 ng/L and 3.10-40.0 ng/L,respectively.At the same time,the current method had good recovery and inter-and intra-day reproducibility in the monitoring of ultra-trace perfluorocarboxylic acids in tap water,Jiulongjiang water,effluent from sewage treatment plant and milk samples.(2)To broaden the application scope of DAVC/MMF,four ultra-trace perfluorophosphoric acids in water and vegetable samples were extracted and analyzed with DAVC/MMF-SPME-HPLC-MS/MS method.The preparation conditions of DAVC/MMF were optimized in detail.The obtained adsorbent was characterized by fourier transform infrared spectroscopy(FTIR),elemental analysis and scanning electronic microscopy.The experimental results showed that under the optimized extraction conditions,the LOD values of analytes in water and vegetable matrix were 0.11-0.86 ng/L and 2.21-55.0 ng/k:g,respectively.The LOQ values were 0.36-2.84 ng/L and 7.37-181 ng/kg,respectively.The recoveries of water samples and vegetable samples were varied from 81.5%to 120%and 80.6%to 110%,respectively.The RSD values of intra-and inter-day reproducibility(n=4)were less than 12%.The results well evidenced that the introduced method possessed ideal sensitivity and accuracy,and had high application value in the detection of perfluorophosphoric acids in environmental water and vegetable samples.(3)To extract perfluoroalkyl sulfonamides effectively,multiple monolithic fiber(FBE/MMF)were synthesized by using 1H,1H,2H,2H-nonafluorohexyl acrylate and vinyboronic anhydride pyridine complex as dual functional monomers and ethylenedimethacrylate as cross-linker.The FBE/MMF obtained under the optimum preparation conditions were characterized by FTIR and so on.Under the optimized conditions,highly efficient and sensitive FBE/MMF-SPME-HPLC-MS/MS method for the determination of ultra-trace perfluoroalkyl sulfonamides in environmental water and urine samples was established.Results showed that FBE/MMF could enrich perfluoroalkyl sulfonamides effectively through fluorophilicity and B-N complexation.The proposed method possessed good linear relationship.The LOD and LOQ values were 0.13-1.45 ng/L and 0.44-4.80 ng/L,respectively.The recoveries of water and urine samples were in the ranges of 80.3%-19%and 80.5%-119%,respectively.The intra-and inter-day reproducibility(n=4)was satisfactory and the RSD values were less than 12%for all analytes in all samples.The results well indicated that the proposed method possessed some merits such as high sensitivity,wide linear range and environmental friendliness.Therefore,it could meet the analytical requirements of ultra-trace perfluoroalkyl sulfonamides in complex environmental water and urine samples.