Scientific Article on Fluorine Mass Balance in PFAS-Contaminated Soil
Eurofins has contributed to a newly published scientific article in the journal Environmental Pollution. In addition to Eurofins scientists, the paper was co-authored by researchers from Örebro University, Sellén & Filipovic, Tongji University (Shanghai), and the City University of Hong Kong. The study focuses on establishing fluorine mass balances in PFAS-contaminated soils using a suite of complementary analytical methods. This publication follows our recent article in Environmental Science & Technology, and—as in that case—the work was financially supported by Eurofins.
The use of aqueous film-forming foams (AFFF) is one of the most widespread sources of PFAS contamination in soils. Due to the chemically diverse nature of PFAS, there is a considerable risk of underestimating the total PFAS burden. Therefore, multiple analytical approaches are typically necessary to obtain a comprehensive assessment. In this study, a stepwise analytical workflow was implemented, comprising total fluorine (TF), extractable organic fluorine (EOF), target PFAS analysis, and the total oxidizable precursor (TOP) assay (i.e. oxidative conversion).
Soil samples (n = 10) from an AFFF-contaminated site in Sweden were analyzed using the methods described above. Concentrations of target PFAS ranged from 50 to 23 000 µg/kg dry weight (DW), with PFOS being the most abundant compound, representing 13–82% of total target PFAS (mean: 53%). Target PFAS accounted for 1–80% of the EOF in the samples. The TOP assay explained an additional 0–31% of EOF. However, a significant fraction of EOF remained unexplained by both target and TOP analyses. Potential reasons include the presence of non-oxidizable PFAS, incomplete precursor conversion, and/or the formation of ultrashort PFAS during the TOP assay. A statistically significant positive correlation was observed between TOP and EOF results, whereas no significant correlation was found between EOF and target PFAS analysis. This suggests that the TOP assay may more accurately reflect overall PFAS load. Another key finding is that total fluorine (TF) analysis does not appear to be a reliable method for assessing PFAS contamination. The study concludes that combining the TOP assay with routine target PFAS analysis is recommended for a more comprehensive quantitative and qualitative understanding of PFAS contamination in soil.
Together with the findings from our Environmental Science & Technology publication, the results from this study have provided valuable input to ongoing development work at the Eurofins PFAS Competence Centre. The integration of target PFAS analysis, TOP assay, EOF, TF, suspect screening, and diverse extraction protocols has deepened our methodological insight into the characterization of PFAS in AFFF-impacted soils.
A link to the open access paper can be found at our publication page
Links
If you have any questions concerning the work please contact the co-authors
Patrick van Hees, e-mail: patrick.vanhees@ftn.eurofins.com
Patrik Karlsson, e-mail: patrik.karlsson@ftn.eurofins.com