Determining PFAS Contamination From Firefighting Foam Using PIGE and PIXE

PFAS, or per- and polyfluoroalkyl substances are man-made chemicals composed mainly of fluorine and are categorized as “forever chemicals.” Once in the environment, they do not break down or disappear. One such PFAS of concern is alcohol resistant aqueous film-forming foams (AR-AFFF). 0.5g targets of AR-AFFF and cellulose were prepared and then bombarded with a 1.8 MeV external proton beam from our 1.1-MV tandem Pelletron accelerator in the Union College Ion Beam Analysis Laboratory. PIGE, or proton-induced gamma-ray emission, was used to screen for fluorine in the AR-AFFF. Fluorine gamma-rays from the fire foam targets were observed and spectra of normalized intensity vs. gamma-ray energy were generated. Concentrations of fluorine in AR-AFFF were determined by using an experimentally determined linear fit to data of fluorine concentration versus gamma-ray intensity taken on a set of NaF and cellulose standards.  Soil samples from sites with known PFAS contamination were created and analyzed using PIGE and PIXE, or particle-induced X-ray emission. X-ray energy spectra were generated and from the characteristic X-rays, elements  heavier than fluorine were detected. Of particular interest and concern was the presence of lead in some of the soil samples. We will illustrate the collection and analysis methods and results on the fluorine by PIGE, and heavy metal concentrations by PIXE, will be presented.