1. Introduction Click to copy section linkSection link copied! Per- and polyfluorinated alkyl substances (PFAS) are a class of recalcitrant and anthropogenic compounds that have been identified as chemicals of concern by state and federal regulatory agencies. (1,2) Use of aqueous film-forming foams (AFFF) for firefighting activities has led to a broad range of PFAS with different structures and chain lengths being detected in groundwater at many military and airport sites.