Passive Sampling for Testing PFAS in Water

Poly- and perfluorinated alkyl substances (PFAS) are a persistent concern for scientists, who are seeking better methods to test for these substances in the environment and in food.

Texture of mussels | Image Credit: © whitestorm - stock.adobe.com

Rainer Lohmann, a professor of oceanography at the University of Rhode Island, spoke about developing better passive sampling methods for detecting PFAS during the Eastern Analytical Symposium (EAS) in Princeton, New Jersey. The U.S. Environmental Protection Agency (EPA) has recommended the maximum concentration of PFAS in drinking water at PFOA and PFOS at 4 ng/L each, with PFNA, PFHxS and Genx at 9–10 ng/L and PFBS at 2,000 ng/L, which makes testing small amounts of contaminants a challenge.

PFAS can enter the environment through packaging, cookware, and processing, according to the U.S. Food and Drug Administration (FDA) (1). Consumption of PFAS is a major health concern for regulatory authorities globally, because of their adverse impact on human health – in some cases increasing risks of cancer, liver damage, and high cholesterol, among other risks.

For this reason, it’s important to be able to test the level of PFAS in the environment over time. Passive sampling, which relies on diffusion to enrich PFAS in a sorbent of choice, allows researchers to analyze the level of PFAS in a sample in time-weighted concentrations, which may be a more accurate method of testing compared to snapshot sampling, Lohmann said. Chemcatcher, diffusive gradients in thin films (DGT), and polar organic chemical integrated samplers (POCIS) are all common methods for sampling PFAS.

During his presentation at EAS, Lohmann focused on the DGT method, calling it a “very nice chemometric approach.” Lohmann’s team used passive sampling methods to test PFAS in ground and ocean water at a variety of locations including the Narragansett Bay in Rhode Island, and in Cape Cod, Massachusetts. On Cape Cod, for example, the team wanted to develop a better understanding of PFAS uptake in fish and mussels (2).

“There’s a lot of concern now about uptake from PFAS now, particularly through fish,” Lohmann said. Lohmann’s team used polar organic chemical integrative samplers (POCIS), and polyethylene tube samplers (PETS) to collect ocean water to evaluate biotic and abiotic uptake in ground water. The researchers discovered 17 PFAS in contaminated groundwater, compared to 9 PFAS in the reference sample – finding the method effective at determining the level of contaminants in the fish.

While passive samplers can be an effective way to measure PFAS in the environment, there are a few considerations scientists need to make, he said. Passive sampling is useful when it’s deployed well, Lohmann said. There are also few equilibrium samplers that have been developed specifically for testing PFAS and understanding the linear uptake time for sampling is key.

References

(1) Center for Food Safety and Applied Nutrition. Per- and Polyfluoroalkyl Substances (PFAS). https://www.fda.gov/food/environmental-contaminants-food/and-polyfluoroalkyl-substances-PFAS. (accessed 2023-11-13).

(2) Barber, L. B.; Pickard, H. M.; Alvarez, D. A.; et al. Uptake of Per- and Polyfluoroalkyl Substances by Fish, Mussel, and Passive Samplers in Mobile-Laboratory Exposures Using Groundwater from a Contamination Plume at a Historical Fire Training Area, Cape Cod, Massachusetts. Environ. Sci. Technol. 2023, 57 (14), 5544–5557. DOI: 10.1021/acs.est.2c06500