Occurrence of ultrashort-chain per- and polyfluoroalkyl substances in water samples from Ohio, Indiana, and Illinois

Ultrashort-chain per- and polyfluoroalkyl substances (PFAS) are the most mobile and potentially the most persistent PFAS analogues. Although well known for their use in different industries, their environmental occurrence and impact still constitute knowledge gaps. This study analyzed sixteen PFAS, with emphasis on five ultrashort-chain PFAS, in samples collected from Ohio (rainwater, surface water, drinking water and wastewater effluent), Indiana (surface water), and Illinois (surface water). Trifluoroacetic acid (TFA) was found in all the samples: 91 ng L -1 in rainwater, 51-123 ng L -1 in drinking water, 41-315 ng L -1 in surface water, and 89-387 ng L -1 in wastewater effluent. Trifluoromethanesulfonic acid (TFMS) was quantified in three samples; the estimated concentration in wastewater effluent was 179 ng L -1 . Perfluoropropanoic acid (PFPrA) was detected in all samples (estimated concentration range 5-144 ng L -1 ), except for rainwater. Overall, these three quantified ultrashort-chain PFAS are more prevalent and occurred at higher concentrations than longer-chain homologues (< 70 ng L -1 ). Perfluoroethanesulfonic acid (PFEtS) and perfluoropropanesulfonic acid (PFPrS) were below the limit of quantification in all samples. This study contributed to filling the knowledge gap of the environmental occurrence of ultrashort-chain PFAS, for which available data are few, particularly in the United States. The results set the foundation for expanded analysis of ultrashort-chain PFAS across more extensive geographic regions and implied the necessity for environmental and health impact studies. Synopsis: High concentrations of ultrashort-chain PFAS were ubiquitously detected in above-ground water samples from the U.S. Midwest, indicating the need for further environmental research. • Ultrashort-, short-, and long-chain PFAS analyzed in water samples from U.S. Midwest. • Trifluoroacetic acid occurred at significantly higher concentrations than longer chain PFAS. • Trifluoroacetic acid detected in rainwater and finished drinking water samples. • High concentrations of trifluoromethanesulfonic acid detected in wastewater effluent