Performance Testing of a Volatile PFAS Method Applicable to Indoor Air, Soil Gas, and/or Sewer Gas

Abstract Description: Currently there is not a standard sampling and analysis method for vapor phase per- and polyfluoroalkyl substances (PFAS) that can be routinely applied to soil gas, sewer/conduit gas, and indoor air samples. To study the potential for PFAS vapor intrusion, a method for the analysis of a set of fluorotelomer alcohols and perfluorooctanesulfonamides was developed and validated. The method includes the active collection of samples in multi-bed sorbent tubes followed by analysis using thermal desorption gas chromatography-tandem mass spectrometry (TD-GC–MS/MS). Method validation steps included the evaluation of desorption efficiency, second source verification, storage stability, and method detection limit determinations. These were successfully completed for the fluorotelomer alcohols and perfluorooctanesulfonamides. Method applications to perfluorocarboxylic acids were also evaluated revealing some potential for artifact formation during thermal desorption. The method performance was evaluated by sampling large volumes of indoor air with and without added humidification (up to 288 liters). Results revealed potential recovery concerns at high humidity. Testing included the simulation of collection of warm high concentration soil gas with the equipment in cold outdoor air. Additionally, recovery testing was performed with the collection of a residential sewer gas sample using spiked sorbent tubes. The method was also tested at three field sites where sample collection included subslab soil gas, deep soil gas, landfill gas and sewer gas. These sites had different soil types, moisture levels, and nontarget compounds providing information about field application feasibility and potential interferences from nontarget compounds.

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