PIGE to Measure AOF Reveals Limited PFAS Removal by Adsorbents in Water

Rapid, gravity‐driven solid‐phase extraction (SPE) using graphitized activated carbon felt (GACF) followed by Particle‐Induced Gamma‐ray Emission (PIGE) spectroscopy is useful for aqueous per/poly‐fluoroalkyl substances (PFAS) screening via measurement of Adsorbable Organic Fluorine (AOF, reporting limit: 100 ppt as F). Moderately high dissolved organic content may compete for PFAS binding sites on the GACF, and inorganic fluoride may result in AOF overestimation due to PIGE's lack of selectivity. Here, sample pre‐treatment with Fenton's reagent and acidification improved method performance by mitigating matrix interferences. The modified method was used to rapidly screen AOF in > 200 surface‐, recycled‐, and ground‐water samples from Orange County, California. Comparison to LC–MS/MS measurements indicated that GACF/PIGE captured substantial additional organic fluorine not measured by targeted methods. GACF/PIGE tests revealed limited removal of AOF by commercial PFAS adsorbents from groundwater in a drinking water treatment application. The current data collected on ultra short chains are insufficient to determine their relative contribution to the total measured AOF and requires further investigation.