Characterization of the Chemical Contents of Fluorinated and Fluorine-Free Firefighting Foams Using a Novel Workflow Combining Nontarget Screening and Total Fluorine Analysis

Abstract

Aqueous film-forming foams (AFFFs) are widely used to extinguish liquid fires due to their film-forming properties. AFFF formulation historically contains per- and polyfluoroalkyl substances (PFASs) that can be very persistent and pose a health risk to biota and humans. Detailed analysis of the chemical composition of AFFFs can provide a better understanding on the potential environmental impact of the ingredients. In this study, a novel workflow combining target analysis, nontarget screening analysis (NTA), total fluorine (TF) analysis, and inorganic fluoride (IF) analysis was applied to disclose the chemical composition of 24 foams intended for liquid fires. Foams marketed as containing PFASs as well as fluorine-free foams were included. By comparing the sum of targeted PFASs and total organofluorine concentrations, a mass balance of known and unknown organofluorine could be calculated. Known organofluorine accounted for <1% in most fluorine-containing AFFFs, and it was confirmed that the foams marketed as fluorine-free did not contain measurable amounts of organofluorine substances. Five fluorinated substances were tentatively identified, and non-fluorinated zwitterionic betaine compounds, which are considered to be replacement substances for PFASs, were tentatively identified in the organofluorine-free foams.

Assessing the Ecological Risks of Per‐ and Polyfluoroalkyl Substances: Current State‐of‐the Science and a Proposed Path Forward

“…Another analytical and assessment challenge is the occurrence of PFAS precursors that can be biotically and/or abiotically transformed to "end use" PFAS (Ellis et al 2004;Harding-Marjanovic et al 2015). Precursors occur in formulations and in the environment but targeted analytical methods to identify specific precursors often are limited in large part due to a lack of standards (Newton et al 2017; Accepted Article Dubocq et al 2019). In any case, both unidentified/unmeasured PFAS and PFAS precursors currently are a challenge for mixture assessment because they contribute uncertainty to our understanding of which PFAS will ultimately interact with ecological receptors.…”

“…The proportion of unidentified PFAAs precursors decreased from sediments to invertebrates and fish, perhaps suggesting biotransformation of the precursors across trophic levels, which could contribute to the biomagnification of some PFAS (Simmonet-Laprade et al 2019).The broad analytical techniques just described allow a crude estimate of the occurrence and identity of precursors and unidentified PFAS. However, it is critical to have robust identification of previously uncharacterized PFAS, which requires LC linked to non-targeted high-resolution mass spectrometry (LC-HRMS)(Dubocq et al 2019;McDonough et al 2019). For unequivocal and reliable PFAS identification and quantification, pure analytical standards must be available; currently, such standards are commercially available for less than 50 potentially relevant PFAS.…”

Isolating the AFFF Signature in Coastal Watersheds Using Oxidizable PFAS Precursors and Unexplained Organofluorine

“…Both legacy (electrochemical fluorination: ECF and fluorotelomer: FT) and contemporary (FT only) AFFF contain large quantities of polyfluoroalkyl precursors, − which may degrade into terminal perfluoroalkyl acids (PFAA) subject to water quality guidelines. ,, PFAS composition in AFFF contaminated surface water and groundwater is expected to change along the hydrological flow path due to preferential sorption and degradation of these precursors. ,,,, Such processes could potentially confound detection and isolation of the PFAS attributable to AFFF contamination at a given location.…”

A Critical Review of a Recommended Analytical and Classification Approach for Organic Fluorinated Compounds with an Emphasis on Per‐ and Polyfluoroalkyl Substances

“…Since the chemicals present in the (injected) sample depend on extraction and purification methods, in practice it is not possible to see all chemicals in a sample (even the unknowns). A recent paper provides an example for the determination of 24 PFAS in firefighting foams using LC/qToF instrumentation (Dubocq et al 2020).…”