Advancing the Environmental Forensics of Per- and Polyfluoroalkyl Substances (PFAS) Through NonTarget Workflows

Understanding the sources of per- and polyfluoroalkyl substances in watersheds has become a top priority given the pervasive nature of PFAS contamination nationally and internationally. Aqueous film forming foams (AFFFs) remain a major source of PFAS that were deliberately discharged to the environment during firefighter training practices and emergencies. However, it has been 20 to 30 years since the discharge of AFFF was largely curtailed by municipal, state, and federal entities. Despite efforts to identify PFAS within AFFF, there remains a limited amount of information on how the fluorinated and non fluorinated composition of AFFF has changed over time, between formulations types (e.g., MilSpec, non-MilSpec, and alcohol resistant), and among AFFF manufacturers. An archived collection of over 200 AFFFs is being characterized by 19F and 1H nuclear magnetic resonance for total organic fluorine, fluoride, and for differentiating electrofluorination from fluorotelomer- based formulations. In addition, a combination of liquid chromatography and gas chromatography combined with high resolution mass spectrometry are being used to discern trends in precursor concentrations and composition as a function of time. Advanced statistical tools and machine learning approaches are being used to identify diagnostic features, track temporal trends, and differentiate AFFF types, and manufacturers.