To Örebro University

This study presents the screening of per and polyfluoroalkyl substances (PFAS) in landfill leachates collected from three sites in Sweden. PFAS are a group of synthetic chemicals that have been gaining global concern as emerging contaminants. When PFAS-containing products are discarded in landfills and not appropriately managed, it leads to the seeping of PFAS into the surrounding environment through leachate and may pose possible risks to different environmental compartments. The strong carbon-fluorine (C-F) bond makes them very persistent in the environment, together with the bioaccumulative characteristics of some PFAS, leading to potential health concerns. For a better understanding of PFAS content in landfill leachates, various analytical approaches were used to analyze 67 PFAS, including neutrals, anionics and zwitterionics in combination with fluorine (extractable organofluorine, EOF) analysis to capture the broader picture of the fluorine content of the leachate samples. A total of 12 leachate samples from 3 sites in Sweden were extracted by solid phase extraction (SPE) using weak anion exchange (WAX) and weak cation exchange (WCX) sorbents. Target screening was done using an Acquity ultra-performance convergence chromatograph (UPC2) coupled with a tandem mass spectrometer (MS/MS) and ultra performance liquid chromatograph coupled with a tandem mass spectrometer (UPLC-MS/MS). Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) dominated the PFAS profile in WAX and WCX extractions. The quantified PFAS concentration in WAX extracts ranged from 767 ng/L to 18400 ng/L. Among the detected and quantified PFAS concentrations, ultrashort-chain PFAS were the most dominant among all the leachate samples. Trifluoroacetic acid (TFA) had a concentration of 12.3 ng/L to 9340 ng/L, perfluoropropanoic acid (PFPrA) was 16.2 ng/L to 2320 ng/l, and trifluoromethane sulfonic acid (TFMS) was 6.50 ng/L to 590 ng/L. TFA, PFPrA and TFMS were detected and quantified in all samples extracted using WAX sorbent with a sum concentration ranging from 60 ng/L to 10500 ng/L. Among the long-chain PFAS, perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were dominant, with a concentration of 19.7 ng/L to 1060 ng/L for PFOA and 11 ng/L to 245 ng/L for PFOS. The sum PFAS concentration range in WCX extracts was 410 ng/L to 7820 ng/L. Screening of four zwitterionic PFAS was performed in the WCX extracts, and their quantified concentration was 0.148 ng/L to 280 ng/L, with the most dominant contribution being from N-(carboxymethyl)-N, N-dimethyl-N-[3-(1H,1H,2H,2H-perfluoro-1-octanesulfonamido)propan-1-yl]ammonium (6:2 FTAB) (N-CMAP-6:2 FOSA). Perfluorooctane sulfonamide (PFOSA), perfluorobutane sulfonamide (FBSA), perfluorohexane sulfonamide (FHxSA), perfluorooctane sulfonamidoacetic acid (FOSAA), ethyl perfluorooctane sulfonamidoacetic acid (EtFOSAA), methyl perfluorooctane sulfonamidoacetic acid (MeFOSAA) were detected and quantified among all sites while ethyl perfluorooctane sulfonamido ethanol (EtFOSE,) and ethyl perfluorooctane sulfonamido ethanol (MeFOSE) were not detected in any of the sample. In the EOF analysis, the concentration of fluorine quantified in WAX extracts was 1930 ng/L F to 35000 ng/L F, and the content of EOF covered by identified fluorine was 0.7% -14.6%. For WCX extracts, EOF ranging from 184 ng/L F to 1410 ng/L F and 1.6% to 17.8 % of the EOF was defined by identified fluorine (ng/L). Most of the EOF consisted of unidentified fluorine chemicals, indicating that target screening alone was insufficient. The results demonstrated that addressing PFAS pollution in landfill leachates demands a thorough strategy that should include target PFAS screening, regulatory measures, efficient management techniques, and continuous surveillance to reduce hazards to human health and the ecosystem.