Aqueous Leaching of Ultrashort-Chain PFAS from (Fluoro)polymers: Targeted and Nontargeted Analysis

Abstract

Fluoropolymers are a class of per- and polyfluoroalkyl substances (PFAS) defined as high molecular weight plastics containing only carbon-based backbones with F atoms directly attached. Here, we used targeted and nontargeted analytical methods to quantify the aqueous leaching of small-molecule PFAS from three types of fluoropolymer tubing material and three types of nonfluorinated polymer tubing material. C₂–C₄ perfluoroalkyl carboxylic acids (PFCAs) were quantified with ion chromatography–mass spectrometry, and C₄–C₉ PFCAs were quantified with liquid chromatography–tandem mass spectrometry. A new ¹⁹F nuclear magnetic resonance (NMR) method with lower detection limits provided an unbiased, nontargeted view of all fluorinated chemicals in the aqueous leachate. C₂–C₄ PFCAs had a higher concentration than longer-chain PFCAs. All tubing tested, including the nonfluorinated polymers, contained trifluoroacetic acid (C₂ PFCA) concentrations above the blank. NMR identified additional fluorinated chemicals, especially in the nonfluorinated PEEK, a common replacement for fluoropolymers in laboratory chromatography systems. Overall, each fluoropolymer tested had different fingerprints of C₂–C₄ PFCAs, which may be related to their synthetic production such as processing aids, residuals, and inhibitors used; fluorinated chemicals were also identified from nonfluorinated polymers. The outcome of this work informs better trace analysis in the laboratory and presents an indication of how fluoropolymers and other plastics can be an emission source to the environment.