PFAS CHEMISTRY

Overview

At the very core of understanding PFAS, whether delineating nature and extent, assessing risk, or treating the compounds, is understanding the chemistry of these compounds. PFAS comprises a large class of several thousand synthetic fluorinated compounds with unique chemical and physical properties. The carbon-fluorine chemical bond is the strongest in organic chemistry, making PFAS resistant to degradation and extremely persistent in the environment. PFAS compounds are also surfactants, making them very mobile in water.

PFAS compounds have been used in many applications for over 75 years, ranging from stain-resistant clothing and carpeting to aqueous film forming foam, a fire suppressant. As a result, there are many sources of PFAS contamination including industrial sites, landfills, wastewater treatment plants, areas where biosolids have been spread, and fire training areas.

With improvements in analytical chemistry instrumentation, PFAS can now be detected in areas where it had not been suspected in the past. Analytical methods continue to improve, with detection now possible in the low parts per trillion. Until recently, there had not been a commonly used EPA analytical method for the analysis of PFAS. EPA Methods 533 and 537 could be used for analysis of finished drinking water samples, but they were not designed or approved for use with other matrices. Another EPA method, Method 8327, has known difficulties with reproducibility, which limits its use as a tool for screening environmental samples.

HGL’s Ongoing Laboratory Validation Project for SERDP

HGL is currently managing a study to validate EPA Analytical Method 1633 through DoD’s Strategic Environmental Research and Development Program (SERDP). This work is in collaboration with the Air Force, Army, Navy, and EPA.

The objective of this study is to generate and compile data to document the precision and accuracy of EPA Method 1633 using the isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) laboratory analytical method for quantitation of PFAS in various media, including wastewater, groundwater, surface water, landfill leachate, soil, sediment, biosolids, and tissues. HGL will compile results of the validation study from 10 commercial and state laboratories for submission to the SERDP team. Method 1633 will be the first EPA-approved method that has been multi-laboratory validated for most common environmental matrices. This much anticipated analytical method will make PFAS data more consistent across laboratories and expand investigation of diverse, potentially affected media.

Click here to see Method 1633.

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