Per- and polyfluoroalkyl substances (PFAS) have been used as fire retardants and nonstick coatings for decades. Previous research has shown that some of the molecules can be persistent organic pollutants that pose health risks. However, getting a handle on those risks—and coming up with appropriate regulations for the chemicals involved—is challenging because most PFAS structures are proprietary, and they get transformed in the environment into unknown products.
To fill in the PFAS picture, environmental chemists have been developing methods to sample these compounds. Now, for the first time, researchers at Nanjing University and the National Institute of Advanced Industrial Science and Technology have developed a method to capture PFAS in both the gaseous and particulate phases of the atmosphere (Environ. Sci. Technol. 2020, DOI: 10.1021/acs.est.9b05457). Their samples, collected from a rooftop in Nanjing using a cryogenic system to select for PFAS homologues and analyzed using high-resolution mass spectrometry, turned up 117 PFAS-like molecules, including several that had not been found in the air before.
Cora Young, an atmospheric chemist at York University who was not involved with the work, says the team’s observation of 12 hydrosubstituted perfluoroalkyl carboxylates (H-PFCAs) in the atmosphere is particularly interesting. The H-PFCAs seem to have different distributions in the atmosphere from their nonhydrosubstituted counterparts, even though their physical properties should be very similar. That observation, she says, suggests that the compounds come from different sources and should be studied in more detail to pin down what industrial activities might be producing them.
“Industry is not telling us what they’re doing,” Young says. “Studies like this are essential for telling us what to look at when we do more targeted analyses of PFAS.”