In a recent PFAS fireside chat, Dr. John Washington from the US EPA discussed the findings of a recent study published in Science that detected a novel group of per- and polyfluoroalkyl substances (PFAS)—called chloroperfluoropolyether carboxylates (ClPFPECAs)—in soil samples from New Jersey. The study, conducted by Dr. Washington and his colleagues, detected 10 unique ClPFPECAs in these samples, with the highest concentrations measured near the Solvay manufacturing plant in West Deptford Townhouse, New Jersey, and decreased amounts detected as the distance from the plant increased.

What did the PFAS study find?

The detected novel ClPFPECAs were found to be structurally similar to many of the well-known “legacy” PFAS compounds, such as perfluorooctanoic acid (PFOA), but with notable exceptions. First, in ClPFPECAs, one of the fluorine atoms is replaced by a chlorine near the end of the molecule, which is what makes them “chloroperfluoro-” compounds. Second, ClPFPECAs contain two ether groups in the carbon backbone. However, ClPFPECAs are similar to PFOA in that they contain carboxylic acid functional groups.

So, why were these ClPFPECAs found near the Solvay plant? As noted in the paper, these novel PFAS chemicals are used as processing aids in the manufacturing of fluoropolymers. Previously, Solvay made its fluoropolymers using Surflon, which contains C9, C11 and C13 perfluorinated carboxylic acids (PFCAs). In 2016, however, several manufacturers, including Solvay, agreed to phase out these long-chain PFCAs. It is uncertain, but the ClPFPECAs detected in the study may be used as replacement compounds for Surflon.

For this study, the research team used a combination of targeted and non-targeted analytical techniques. As noted by Dr. Washington, the non-targeted analysis methods were essential to finding these novel PFAS compounds. For example, the distinctive isotope signature of chlorine was used to confirm its presence in the molecules. In addition, techniques such as Kendrick mass defect analysis and the identification of common, diagnostic fragments were used to find other ClPFPECAs in the soil samples.

What do the findings improve our understanding of PFAS risks?

So, what happens to these novel PFAS in the environment? While that’s still unclear, Dr. Washington’s group is involved in investigating transformation at the chlorine site of the molecule, which may indicate that the ClPFPECAs can form other novel PFAS. Stay tuned for the results of this research.

Although the ultimate risk of ClPFPECAs to human and wildlife health remains unknown, this study eloquently demonstrates how mass spectrometry—specifically high resolution accurate mass spectrometry instruments—can be used to improve our understanding of the PFAS “dark matter” that exists in our environment.

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