Quantification of per- and polyfluoroalkyl substances (PFASs) in aqueous film-forming foam (AFFF)-impacted water: Comparisons between methodologies and laboratories.

The widespread use of aqueous film-forming foam (AFFF) for firefighting and firefighter training has led to extensive per- and polyfluoroalkyl substance (PFAS) contamination in the environment. Various solid-phase extraction (SPE)-based methods have been widely used for preconcentrating PFASs and as a cleanup step prior to liquid chromatography mass spectrometry analysis. However, challenges remain in the analytical determination of PFASs via SPE methods, especially for cations and zwitterions at AFFF-impacted sites. Herein, we report the results of an interlaboratory and multi-method evaluation of SPE-based analyses of PFASs in AFFF-impacted water. We quantified PFAS levels by conducting an inter-method evaluation and an interlaboratory comparison. In the SPE-based method comparison, enhanced PFAS recoveries by replacing the formic acid in methanol rinse step with an aqueous rinse were reported for cationic and zwitterionic PFASs. There was great agreement between laboratories for both the direct injection and SPE-based analyses (relative standard deviation ∼32 % and 40 %, respectively). Sources that contributed to the variance in this study included minor differences in SPE extraction conditions and analytical methods employed by each laboratory, as well as the pairing of different isotope-labeled internal standards. The results of this study will aid the analytical community and support future PFAS measurements.