The primary objective of this project is to take an established total fluorine method and develop it into a field-screening method for per- and polyfluoroalkyl substances (PFAS). Specifically, the project will develop the Particle-Induced Gamma-ray Emission (PIGE) spectroscopic method of fluorine detection into a field-deployable technique that can rapidly screen groundwater, surface runoff, soils and sediments for the presence of environmentally relevant concentrations of PFAS in the field. There are two “high risk” aspects to this project: (1) the miniaturization of the accelerator system that can perform these measurements in the field and (2) the development of the pre-concentration methods that will achieve sensitivity to PFAS down to current Health Advisory Limits (HALs). Thus, the project will lower the beam energy as well as the method detection limits (MDLs) to demonstrate feasibility of this approach with commercially available equipment.
The ion beam analysis technique, PIGE, has been demonstrated to provide a quantitative measure of total fluorine on the surface of a variety of materials, including papers, textiles, and the surface of solid-phase extraction media that concentrate PFAS from aqueous samples. Unlike traditional chemistry approaches, PIGE is a spectroscopic technique that can achieve the desired sensitivity within 1 to 3 minutes per sample, with little sample preparation other than solid-phase extraction for aqueous samples. This makes PIGE a leading candidate for a field-deployable method for PFAS detection. Currently, 50 mL aliquots of environmental water samples yield a detection limit around 10 parts per billion for total fluorine, which typically is sufficient for site characterization of aqueous film-forming foam (AFFF)-impacted sites because there are so many PFASs present and each has 10-20 fluorine atoms per molecule. However, ten-fold lower detection limits for field screening would mean detection limits appropriate for the HALs for PFAS in drinking water. Similarly, the current PIGE method is laboratory-based, and would need to be smaller and self-contained to be field-deployable. Bench-scale experiments will be performed to scale up sample volumes with commercially available high-volume sampling systems and demonstrate that PIGE limits of detection can scale with sample volume directly. Second, the lowest energy (and therefore the smallest commercially available accelerator) at which the PIGE method will work for total fluorine analysis will be determined.
The development of a method for in situ total fluorine screening will allow the characterization of AFFF-impacted sites to be rapid, accurate and significantly less expensive. The drilling of test wells and sampling of groundwater, surface water, and sediments at the same time as a rapid test for PFAS concentration will shorten the site characterization process significantly. The savings on site-characterization costs alone could potentially reach hundreds of millions of dollars, and when remediation activities commence, the subsequent monitoring of progress will be possible by PIGE as well. Because of the speed with which site characterization could be performed, it will be feasible to consider characterizing all AFFF-impacted DoD sites within a decade, which is inconceivable with any current methodology.
Tighe, M., Y. Jin, H.D. Whitehead, K. Hayes, M. Lieberman, M. Pannu, M.H. Plumlee, and G.F. Peaslee. 2021. Screening for Per-and Polyfluoroalkyl Substances in Water with Particle Induced Gamma-Ray Emission Spectroscopy. ACS ES&T Water, 1(12):2477-2484.
Wilkinson, J.T., S.R. McGuinness, and G.F. Peaslee. 2020. External Beam Normalization Using Atmospheric Argon Gamma Rays. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 484:1-4.