The overall goal of this proof-of-concept project is to develop robust analytical methods to determine total organic fluorine in per- and polyfluoroalkyl substance (PFAS)-free aqueous firefighting formulations using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). Specifically, the following will be evaluated: 1) a pretreatment step for concentrating foam by bench-scale foam fractionation; 2) PFAS levels (especially ultra-short chain) in the foam and residual liquid and the effects of formulation constituents on foam formation; and 3) the application of foam analysis using HR-CS-GFMAS.

A bench-scale foam fractionation method will be developed to quantify total PFAS as total organic fluorine (F) content. Experiments will examine the foam formation using PFAS-free formulations, including, but not limited to, National Foam NFD 20-391, Fomtec ENVIRO 2-3% FFF, National Foam AVIO F3 Green KHC 3%, and NRL 502W Siloxane-based Formulation, which contain different types of surfactant-polymer mixtures.

Total F content in the separated foam and residual water will be analyzed with HR-CS-GFMAS and the results will be compared to combustion ion chromatography (CIC) for total F determination. This will allow for a direct comparison of two different analytical methods for total fluorine determination in PFAS-free firefighting formulations with complex matrixes. PFAS fractionation in the foam will be determined by liquid chromatography quantitative time-of-flight mass spectrometry (LC-QToF) together with an extensive nontarget screening list of PFAS. The results will be used to identify surfactant amendments that increase foam formation to increase PFAS recovery, especially short-chain PFAS.

Successful completion of this research will provide fast and cost-effective analytical methods to determine total PFAS and total F content in PFAS-free firefighting formulations. Foam fractionation as a pretreatment step is expected to improve the limit of quantification to reach the targeted level of one part per billion total PFAS, which is a requirement of the National Defense Authorization Act in 2020 for the replacement of traditional firefighting formulations with PFAS-free formulations. (Anticipated Project Completion - 2024)