Screening for Per- and Polyfluoroalkyl Substances in Water with Particle Induced Gamma-Ray Emission Spectroscopy

A new method for rapidly screening drinking water for the presence of per- and polyfluoroalkyl substances (PFAS) has been developed. This method involves gravity filtering drinking water through an activated carbon felt and subsequently analyzing the surface of the felt with particle induced gamma-ray emission (PIGE) spectroscopy. Using this technique, the total fluorine measurements by PIGE produced linear calibration curves adequate to measure below 50 ppt total fluorine from PFAS in drinking water for as little as 2 L of sample. Inorganic fluoride and PFAS were successfully differentiated by acidifying the sample prior to filtration. Acidification did not affect the anionic PFAS binding to the activated carbon filter, while the inorganic fluoride did not bind to the filter below pH 2. This method is quantitative when measuring individual PFAS; however, as a total fluorine measurement, PIGE cannot differentiate between individual PFAS in a mixed solution. Since most environmental or drinking water samples will likely contain a mixture of PFAS, this method could be used as a preliminary screening tool to identify samples with elevated total extractable organo-fluorine from anionic PFAS that can be analyzed by compound-specific methods subsequently to quantify individual analytes.