Furthering the Capabilities of Diffusive-Gradient Passive Samplers for Per- and Polyfluoroalkyl Substances.

Per- and polyfluoroalkyl substances (PFAS) are chemical pollutants of growing concern for many stakeholders. Due to their ubiquity, persistence in the environment, and potential for toxicity at low environmental concentrations, it is necessary to have convenient and reliable methods to measure PFAS in natural waters. Passive sampling methods (in situ preconcentration of PFAS) may be suitable for monitoring situations. One passive sampling design successfully employed for other, well studied contaminants (e.g., methylmercury) is the diffusive gradient in thin film sampler (DGT). However, the application of DGT for PFAS requires development and validation. Here, we iterate on previous PFAS-DGT studies by introducing a redesigned diffusive gradient sampler for PFAS in water and show that it reliably measures 25 PFAS in water, consistent with diffusion theory. Diffusion and whole-sampler uptake rates consistently agreed with model predictions within ±50% relative difference, including when tested at cold temperature (5 °C). In field and laboratory deployments, DGT samplers measured PFAS concentrations within ±23% of grab sample results on average in each case─better performance than codeployed microporous polyethylene tube passive samplers. Based on the evidence in this study, the DGT passive sampler is a promising tool for consistently and accurately passively sampling PFAS in natural waters.