The ubiquitous presence of per- and polyfluoroalkyl substances (PFAS) in water, sediment, and air has highlighted the need for more effective and robust monitoring tools for these unique chemicals. The large sample volumes and high sample numbers required for analysis have limited understanding of spatiotemporal variations in PFAS concentrations in the environment and during remediation. To overcome these limitations, we applied anion-exchange membranes as passive samplers for 19 structurally diverse PFAS, including perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, fluorotelomer sulfonates, and perfluorooctane sulfonamides. Ten anion-exchange membranes with different ion-exchange capacity, thickness, and reinforcing material were evaluated. Batch sorption tests were conducted with environmentally-relevant PFAS concentrations in different solutions, including 10 – 100 mM NaCl, real groundwater, and real pond water, under well-mixed and static conditions. Aqueous- and membrane-phase PFAS concentrations were measured, and the results confirmed that ion exchange was the dominant uptake mechanism. The FAD-PET-75 membrane exhibited the best performance based on the magnitude of the selectivity coefficients and the efficiency of PFAS extraction. The selectivity coefficients for PFAS over chloride varied by class and chain-length (<i>e.g.</i>, 37 for PFBA, 1,350 for PFBS, 390 for PFHxA, and 16,416 for PFHxS), but the relatively tight range of selectivity coefficients allowed concurrent measurement of both short- and long-chain PFAS. Matrix effects related to the total dissolved salts concentration were successfully corrected using a single Setschenow constant. Over 80% of the sorbed PFAS were extracted (for quantitative analysis) by dissolving 1 g L<sup>-1</sup> (or less) of the FAD-PET-75 membrane in methanol. Overall, the results indicated that the FAD-PET-75 membrane is a promising passive sampler material for chemically diverse PFAS.

Anion-exchange membranes for passive sampling of per- and polyfluoroalkyl substances

ACS Spring 2022

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