A pilot study of per- and polyfluoroalkyl substances in automotive lubricant oils from the United States

Abstract

Abstract Per- and polyfluoroalkyl substances (PFASs) were reported to be used as additives in automotive lubricant oils and hydraulic fluids, to reduce surface tension, prevent fires and evaporation. Little is known, however, with regard to the occurrence of PFASs in automotive lubricants. In this study, concentrations and profiles of 13 perfluoroalkyl acids (PFAAs), encompassing nine perfluoroalkyl carboxylic acids (PFCAs; C4–C12) and four perfluoroalkyl sulfonic acids (PFSAs; C4–C10), were determined in 18 automotive lubricants purchased in the United States. The lubricant extracts were analyzed before and after oxidization, to measure PFAAs and their precursors, using the total oxidizable precursor (TOP) assay. Following oxidation, lubricant extracts yielded ∑ PFAA concentrations up to two orders of magnitude higher (range: 196–8300 ng/g; mean: 1840 ng/g) than those measured prior to oxidation (5.96–344 ng/g; 71.6 ng/g), which suggested the presence of notable amounts of PFAA precursors. Long-chain PFCAs (C8–C12;​ ∼ 70% of total) were the major PFASs detected (prior to oxidation). The mean molar increase in the concentration (pM/g) upon oxidation of lubricant extracts varied among the nine PFCAs in the following decreasing order: C4 (1350) > C12 (670) > C11 (570) = C5 (570) > C10 (460) > C9 (300) > C7 (140) = C6 (140) > C8 (110). Principal component analysis of PFCA profiles revealed that PFAAs originate from their respective precursors.