Non-Targeted Analysis (NTA) of Plasma and Liver from Sprague Dawley Rats Exposed to Perfluorohexanesulfonamide (PFHxSA), a Precursor to Perfluorohexane Sulfonic Acid (PFHxS)

High-resolution accurate mass non-targeted analysis (NTA) is a useful discovery tool for metabolite characterization of in vivo dosing studies since it enables detection of both predicted and unexpected biotransformation products. We used NTA to investigate biotransformation of perfluorohexanesulfonamide (PFHxSA) in plasma and liver from male and female Sprague Dawley rats after a 5-day repeat exposure study. PFHxSA is an emerging per- and polyfluoroalkyl substance (PFAS) with unknown toxicity and a potentially reactive headgroup. NTA revealed the presence of predicted in vivo biotransformation products (BP) such as perfluorohexane sulfonic acid (PFHxS) and perfluorohexanesulfinic acid (PFHxSi). PFHxSi also has unknown toxicity and has not, to our knowledge, been previously reported as a PFHxSA BP in mammals. Multiple perfluoroalkyl ether sulfonamides, associated BPs, and novel PFAS were also detected in rat plasma and liver. We observed sex-specific distributions of the dosed compound and BPs, suggesting different toxicokinetics and biological responses. The presence of a complex mixture of predicted and unexpected PFAS in plasma and liver not only mimics the complexity of environmental exposure but also highlights the need for toxicity testing with mixtures and a more complete assessment of dosing solution purity.