Suspect screening and nontargeted analysis of polyfluoroalkyl substances in Lake Huron water and biota

Abstract

Nontargeted analyses (NTA) have identified numerous unknown/novel per- and polyfluoroalkyl substances (PFAS) in water, aqueous film-forming foam, and commercial products, but few studies have used nontargeted approaches to analyze PFAS in aquatic organisms. This study employed NTA to investigate PFAS profiles in the Lake Huron water and biota, including zooplankton, dreissenid mussels, selected prey fish, and lake trout (Salvelinus namaycush). Five suspect perfluoroalkyl acids (PFAA) precursors and perfluoroethylcyclohexane sulfonate (PFECHS) were detected in the water and biota without the use of reference standards. Notably, N-ethyl perfluorooctane sulfonamido acetate (EtFOSAA) was detected in deepwater sculpin (Myoxocephalus thompsonii), PFECHS was detected in water and deepwater sculpin, and N-methyl perfluorooctanesulfonamido acetate (MeFOSAA) was detected in bloater (Coregonus hoyi). Different species are likely exposed to different PFAS due to variations in habitat and food sources. However, PFAS may also bioaccumulate in both prey and predator through foraging. To verify this hypothesis, unknown PFAS features observed in two or more composites from each species were isolated. The unknown PFAS with estimated concentrations >0.5 ng/g wet weight, and biomagnification factors (BMF) >1 were then isolated from all PFAS candidates detected in the food web components, particularly those identified in both prey and predator species. This subset of PFAS features was then slated for structural elucidation. A total of 66 unknown PFAS were detected in the biota and 19 in the water, with proposed structures containing carboxylic, ether, thiol, sulfonyl, amino, and amide groups.