Release of Volatile Per- and Polyfluoroalkyl Substances from Aqueous Film-Forming Foam

Abstract

Research on per- and polyfluoroalkyl substances (PFASs) released from aqueous film-forming foams (AFFFs) has primarily focused on soil and groundwater contamination, or atmospheric transport. However, gas-phase PFAS release from AFFF has not been well examined. We investigated the presence of volatile PFASs in the headspace above agitated AFFF concentrate produced within the past two years using two analytical techniques. One method utilized polyurethane foam and XAD resin with liquid chromatography mass spectrometry to quantify 30 PFASs and is similar to methods used by others to measure PFASs in air. A second, more exploratory approach used a thermal desorption sampler and gas chromatography and mass spectrometry (GC-MS) to measure 22 PFASs. Sixteen PFASs were detected in the headspace, including five fluorotelomer alcohols (0.5–38.1 μg/m3), 10 perfluorinated carboxylic acids (0.4–13670 μg/m3), and one fluorotelomer sulfonate (72.1 μg/m3). The most abundant PFAS detected in the headspace was perfluorooctanoic acid (13670 μg/m3), although it was detected only by GC-MS. Five additional fully fluorinated, iodinated, and ethenyl fluorocarbons were identified but not quantified. It is likely that firefighters are exposed to these compounds, but the risk is not yet known.

PFAS fate and destruction mechanisms during thermal treatment: a comprehensive review

“…63 A recent study evaluated the gas phase PFAS could release from agitated AFFF and concluded that PFOA was the most abundant PFAS detected in the headspace, followed by perfluorohexane and four other iodinated and ethenyl fluorocarbons. 64…”

Comment on “Release of Volatile Per- and Polyfluoroalkyl Substances from Aqueous Film-Forming Foam”

“…In this comment, PFOA denotes the anionic species of the compounds, whereas PFOA-H denotes the protonated form. Note that Roth et al did not differentiate between PFOA and PFOA-H. 1 Roth et al sampled the AFFF headspace with thermal desorption (TD) tube and XAD/PUF samplers and analyzed them using gas chromatography with mass spectrometry (GC-MS) and by liquid chromatography with tandem MS (LC-MS/ MS), respectively. Roth et al also injected a methanolic standard of PFOA-H onto a TD tube for analysis by GC-MS.…”

“…Roth et al did not report a molecular ion and only reported the retention time and fragmentation pattern for the PFOA-H directly injected onto the GC/MS. They observed mass-to-charge (m/z) 69 (CF 3 ), 119 (C 2 F 5 ), 131 (C 3 F 5 ), and 169 (C 3 F 7 ), 1,2 which are characteristic of several highly fluorinated subclasses (including fluorotelomer alcohols, perfluoroalkyl iodides, ethyl perfluoroalkane sulfonamides) and, thus, are not unique to PFOA-H/PFOA. 3,4 Moreover, the PFOA-H fragmentation pattern in Figure S3 of Roth et al does not match the NIST MS spectrum of PFOA-H. 5 In fact, in their Figure S3, perfluoro-1-heptene (PFHP) gave the best match compared to PFOA-H, which gave the sixth best match.…”

“…T he work by Roth et al concerned the profile of per-and polyfluoroalkyl substances (PFAS) in air-phase samples taken over an aqueous film-forming foam (AFFF) solution. 1 We question the identification of perfluorooctanoate (PFOA) and other perfluorocarboxylates (PFCAs) in the headspace of an AFFF solution. In this comment, PFOA denotes the anionic species of the compounds, whereas PFOA-H denotes the protonated form.…”

“…3,4 Moreover, the PFOA-H fragmentation pattern in Figure S3 of Roth et al does not match the NIST MS spectrum of PFOA-H. 5 In fact, in their Figure S3, perfluoro-1-heptene (PFHP) gave the best match compared to PFOA-H, which gave the sixth best match. 1,6 Although Roth et al did not report the observed retention time or fragments for the headspace analysis of AFFF or the PFOA-H standard spiked onto the TD tubes, they concluded that PFOA was present, presumably because the retention time and fragments matched that of their directly injected standard. For these reasons, it seems unlikely that Roth et al detected intact PFOA by TD-GC/MS in the headspace over an AFFF.…”