The environmental prevalence of per- and polyfluoroalkyl substances (PFAS) has led to the development of PFAS-free firefighting formulations. To confirm these new formulations are truly free of PFAS, there is a need to quantify the total PFAS in these complex mixtures. The objective of this project is to develop a standard operating procedure (SOP) for quantifying total PFAS in PFAS-free firefighting formulations with a detection limit of less than 1 part per billion (ppb) of fluorine.

This project's approach relies on two total fluorine quantification techniques – combustion ion chromatography (CIC) and particle-induced gamma-ray emission (PIGE) spectroscopy. Combined with a unique separation procedure to extract background fluoride and remove potentially interfering compounds, we hypothesize this approach will provide quantification of total PFAS in firefighting formulations with a detection limit below 1 ppb. In the first task, the SOP will be established using known model solutions containing analytically problematic constituents such as fluoride and co-occurring surfactants. The detection limit will be first established in an aqueous matrix containing only fluoride and a model PFAS mixture. Then the SOP will be validated for this matrix with the addition of high concentrations of potentially interfering constituents found in PFAS-free firefighting formulations. In the second task, the SOP will be applied to PFAS-free firefighting formulations provided by the Department of Defense to quantify total PFAS.

Developing PFAS-free firefighting formulations is a critical, long-term sustainability goal of the Department of Defense. The development of an SOP that can confirm the absence of PFAS will be key to achieving this goal. The SOP will also have a broader use in the consulting and academic community, as it will provide a robust method for separating fluoride and other interfering compounds in liquid samples for the analysis of total PFAS. (Anticipated Project Completion - 2024)