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The PPM Blog

Did We Pass The PFAS Test?

Mélanie Turgeon smiling for the cameraContributed by Regan Wray, Staff Scientist, PPM Consultants

As Keith Pyron’s previous “PFAS, Did We Save the Worst for Last?” article mentioned, per- and polyfluoroalkyl substances (PFAs) “may be the most widespread contaminant.” The EPA is in the process of finalizing the proposed rule that two PFAs be listed as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which is also known as Superfund, in order to make releases more publicly known and to hold responsible parties accountable. Also, recently EPA has proposed the National Primary Drinking Water Regulation (NPDWR) for six PFAs in an effort to prevent deaths and illnesses. Since more regulation is being proposed and finalized, laboratory test methods are constantly being developed and evaluated by EPA.

There are two analytical methods approved by the Environmental Protection Agency (EPA) to analyze drinking water samples for PFAS, and they are EPA Methods 537.1 and 533. These methods focus on short-chain PFAs. Method 537.1 is able to detect and report 18 different PFAs, and Method 533 is able to detect and report 25 different PFAs. The 537.1-method reports 4 PFAs that are not included in Method 533, and Method 533 reports 11 PFAS that are not included in the Method 537.1. The two methods are able to report a total of 29 PFAS combined. One big difference in the methods is that Method 537.1 does not use isotope dilution, which is considered the “gold standard” for reporting to parts per trillion (PPT).

Of course, not all shallow groundwater is considered drinking water, and there are other medias sampled, such as groundwater and soil through the Clean Water Act (CWA) and biosolids and sediment under the Resource Conservation and Recovery Act (RCRA). This creates the perfect introduction to the EPA’s and U.S. Department of Defense’s (DoD) joint effort of Draft Method 1633.  Method 1633 is currently in the multi-lab validation stage, but provides a method for sampling eight different medias (wastewater, surface water, groundwater, soils, biosolids, tissues, leachate, and sediment). This method has a result expansion that includes 40 different PFAs that can be identified.  The 40 PFAs include short and longer-chain PFAs – unlike Methods 533 and 537.1. This inclusion of longer-chain PFAs actually allows sources to be traced by identifying common PFAs found in certain sources. One example provided by Pace Analytical is the identification of 5:3 fluorotelomer carboxylic acid (FTCA), which is dominantly released from a landfill source. Although the Draft Method 1633 provides a wider and more extensive list, it still only scrapes the surface of potential PFAs present – since thousands of long-chain PFAs exist that still cannot be detected with current methods.

Who knows if a testing method will ever be developed to include the more than 9,000 PFAs identified already, but there is an analysis available that can act like a small window to the bigger picture. The majority of PFAs are classified as pre-cursors because they are longer chains that will break down to short-chain PFAs over time. A laboratory analysis procedure named the Total Oxidizable Precursor Assay (TOP) analysis uses heat and oxidative chemicals to speed up the degradation process. This allows the longer-chain PFAs that cannot be detected in the current methods to break down to detectable short-chain PFAs so that a more accurate picture of the full presence of PFAs can be determined. The TOP analysis can reveal the future PFAs concentrations as natural degradation continues in the sampled media or area.

While the PFAS contamination tests affect our environment and human health, new laboratory testing is consistently being developed to be one of the tools to identify the problem, and hopefully confirm the remediation of the problem soon!  If you want to talk about PFA’s, please feel free to reach out to me at


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