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June 2021 – PFAS Detections in Vapors and Other Sensational Oddities

PFAS Detections in Vapors and Other Sensational Oddities

Traditionally when we read about per- and polyfluoroalkyl substances (PFAS), the primary focus relates to drinking water/groundwater and consumer products. As the characteristics of these compounds are further studied, greater attention quickly centers on the air we breathe and the need to understand the dynamics of PFAS existing in our ambient air. PFAS source emissions are not currently regulated at the federal level; however, Michigan, New Hampshire, and New York have enacted (or proposed) limits on PFAS in air emissions. One needs to think about how PFAS move through the various water/solid/air compartments by mechanisms such as diffusion, dispersion, advection, infiltration, abiotic and biotic transformations, and atmospheric deposition to quickly conclude that the monitoring and regulating of PFAS will likely garner quite a bit of attention in the future.

Looking at the numerous PFAS structures, volatility is generally related to the “head” and “tail” PFAS functional groups. Consider the Henry’s Law Constants and published vapor pressure – the currently targeted PFAS can be viewed as volatile or semivolatile; most of the fluorotelomer alcohols (FTOHs), methyl/ethyl fluorooctane sulfonamides (FOSA) and sulfonamidoethanols (FOSE) are considered volatile and practitioners even suggest that some fluorotelomer sulfonate (FTS) and perfluorocarboxylic Acid (PFCA) and their precursors are also volatile.  When one thinks about PFAS as being a volatile organic compound, thoughts quickly gravitate to the possibility of human exposure to PFAS via vapor intrusion. In fact, online searches quickly lead to a variety of PFAS monitoring studies focusing on PFAS air emissions originating from publicly owned treatment works (POTWs), municipal landfills and PFAS off‑gassing from organofluorine-containing firefighting foams.

Like many of our current-day volatile and semivolatile compounds of interest that are examined in air, a number of options for sampling and analysis are available. Specifically, volatile and semivolatile PFAS can be sampled by using single- or multi-staged adsorbent cartridges, silica-lined pressurized cans, OTM-45 samplers, impingers and various passive adsorbent samplers. PFAS analysis has been shown to be accomplished using a modified US EPA TO-17 (thermal desorption/gas chromatography/mass spectrometry [TD/GC/MS]) and the ever-popular modified US EPA Method 537 or 533 (liquid chromatography/tandem mass spectrometry [LC/MS/MS]) following media extraction.

Environmental Standards’ consulting Chemists have a PFAS knowledge base that is on the leading edge of PFAS sampling and analytical technologies, and our Chemists support clients during the early phases of program development and provide sampling and analytical oversight during program execution.

Rock J. Vitale, CEAC

National PFAS Leader/Senior Principal Chemist