Recently, poly- and perfluoroalkyl substances (PFASs) derived from aqueous film forming foams (AFFF) were measured at relatively high levels in effluent in some San Francisco Bay Area wastewater treatment plants. A follow-up study was commissioned to investigate the fate of PFASs at an airport wastewater treatment plant before, during, and after a major AFFF introduction event. Electroplating wastewater that also contributes flow to the airport treatment plant was separately analyzed as another potential source of PFAS. In addition to routine analysis of PFASs by LC-MS/MS, transformation products were identified using high resolution quadrupole time of flight mass spectrometry (QTOF/MS).  Using a combination of targeted and non-targeted approaches, molecular features that were extracted from the raw total scan chromatography were tentatively identified with compounds from an in-house PFAS database. For compounds without a database match, chemical formulas were generated based on exact mass, isotope distribution, and isotope spacing. We preliminarily identified the presence of various PFASs in AFFF formulations, such as 6:2 fluorotelomermercaptoalkylamido sulfonate (FtTAoS), 6:2 fluorotelomer sulfonamide alkylbetaine (FTAB), and two transformation products from the biological oxidation of 6:2 FtTAoS. The integrity of the analysis was validated by standardized sample analysis procedures using Agilent MassHunter Qual and Mass Profiler Professional (MPP) software for multivariate analysis, and high match scores (&gt;90) for the assignments. Available isotope labeled and natural PFAS standards were used as positive controls. The unknown screening approach is critical in establishing transformation reactions and their rates because there are only a few commercially available analytical standards that are applicable to the PFASs present in AFFF. Profile comparisons between different wastewater samples (industrial total effluent vs. electroplating effluent) also help to appoint PFAS sources in wastewater system and assess potential impact to the Bay water system.

Identifying Poly- and Perfluoroalkyl Substances (PFAS) transformation products in a wastewater treatment plant

253rd National Meeting (2017)

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