This project will address the development of a novel equilibrium passive sampling methodology for per- and polyfluoroalkyl substances (PFAS). A range of functionalized polymeric thin films and polymer-inclusion membranes (PIMs) will be developed and tested for use in equilibrium passive sampling of representative USEPA 24 PFAS compounds. The overarching goal is to move away from a kinetic sampler like the Polar Organic Chemical Integrative Sampler (POCIS) to an equilibrium passive sampler similar to the current state of the art for hydrophobic organic compounds.
The following tasks will be carried out in this proof-of-concept project to develop an equilibrium passive sampler for PFAS:
- Development of novel polymeric thin films for equilibrium passive sampling that will be either solid or liquid sorbents embedded in a thin polymer sheet;
- Equilibrium partitioning studies with PFAS covering a range of properties and the interpretation of isotherm data based on sorption models;
- Testing equilibrium reversibility for the top two choices of polymers and assessing the use of performance reference compounds to quantify the extent of equilibrium;
- Evaluating mechanisms of the sorption process.
This proof-of-concept project, if successful, can be extended to a full project to perform the next stage of testing in increasingly complex water matrices to develop the first equilibrium passive sampler for the full range of PFAS.
Several DoD sites are addressing new regulations that are bringing greater scrutiny on the impacts from use of PFAS-containing Aqueous Film Forming Foams (AFFFs). These major changes in the regulatory side have created the need for accurate assessment of risk to humans and ecosystems from the presence of PFAS. While equilibrium passive samplers are increasingly well established for neutral organics, no comparable device has achieved wide acceptance for measuring amphiphilic PFAS. This effort seeks to develop such a sampler, with the goal of enabling reproducible measurements of bioavailable PFAS and allowing improved risk assessment and management for PFAS-contaminated sites by accurately measuring the freely dissolved concentration. The sampler would also enable time integrated measurements in sediments, surface water, and groundwater, and allow efficient determination of Cfree necessary for phase partitioning calculations. A successful PFAS equilibrium passive sampler can be integrated with the current practice of passive equilibrium sampling for organic compounds, not just in the device and deployment aspects, but also in the data interpretation and framework for use in risk assessment. (Projected Completion Date February 2021)