This proof-of-concept project will measure the performance of various adsorbents to extract per and polyfluoroalkyl substances (PFAS) from aqueous film-forming foam (AFFF) and PFAS-free firefighting formulations. The ability of adsorbents to exclude fluoride ions will also be tested. Recovered extracts will be analyzed for total organic fluorine to ensure <1 part per billion (ppb) detection limits and by HPLC-MS/MS as a secondary analytical validation tool.

The requirement of measuring <1 ppb PFAS in PFAS-free firefighting formulations, as specified in draft MIL-PRF-XX727, will require extraction to pre-concentrate PFAS in the absence of novel analytical methods of sufficient sensitivity. Osorb®-type adsorbents developed for passive sampling have been shown to be effective in extracting PFAS from a diverse range of environmental samples (including groundwater, surface water, and sediment) and relatively extreme matrix conditions (e.g., pH, total dissolved solids, organic carbon).

The Osorb® passive sampler design will be optimized for laboratory use to extract and concentrate PFAS from PFAS-free firefighting formulations. After extraction, desorbed PFAS can be analyzed either by mass spectroscopy to measure target PFAS analytes or by standard methods to measure total organofluorine. The use of hydrophobic-amine Osorb® is hypothesized to selectively bind PFAS/organofluorine over fluoride to eliminate interferences. In addition, other Osorb-type adsorbents will be tested and benchmarked against Oasis® WAX solid phase extraction cartridges and other Oasis® ion exchange resins. The project seeks to leverage existing passive sampling protocols and analytical techniques to create a straightforward procedure that can be readily adopted by production and commercial labs. If successful, a standard operating procedure will be developed for use in multi-lab validation studies.

Measurement of PFAS in PFAS-free firefighting formulations at the 1 ppb level is a high priority. This project will leverage analytical expertise and PFAS absorbent technology that has already been developed. The project will screen Osorb-based PFAS adsorbents with concurrent benchmarking to Oasis WAX and similar resins. Adsorption will be tested using standard solid phase extraction approaches and using a passive sampling approach. The goal is to deliver rapid results on whether extraction of PFAS is possible for total organofluorine analysis methods. (Anticipated Project Completion - 2024)