Direct thermal desorption-gas chromatography-mass spectrometry for screening volatile PFAS and side-chain...

Fluorotelomer alcohols (FTOHs) are volatile per- and polyfluoroalkyl substances (PFAS) used in consumer products that contribute to human exposure and environmental contamination. Traditionally, FTOHs are measured in consumer products by solid-liquid extraction coupled with gas chromatography-mass spectrometry (GC-MS). Herein, we optimized a direct thermal desorption (DTD)-GC-MS method to screen for five n:2 FTOHs (n = 4, 6, 8, 10, 12) in 13 food contact materials purchased between 2020 and 2026. Method optimization established a 20 min desorption at 200 °C, achieving an average recovery of 114% and detection limits ranging from 20-53 pg for FTOHs. The method was further extended to include secondary FTOHs, fluorotelomer iodides, fluorotelomer acrylates, fluorotelomer olefins (FTOs), and fluorotelomer methacrylates. The DTD of three popcorn bags and an 'ecofriendly' paper plate at 200 °C generated 6:2 FTOH and 6:2 FTO at concentrations above the quantifiable range due to the thermal degradation of a 6:2 fluorotelomer side-chain fluoropolymer (SCFP). Even after multiple rounds of desorption, 6:2 FTOH and 6:2 FTO were continuously released, albeit at decreasing concentrations, and served as an indicator for the presence of SCFPs. Simulated heating experiments at a realistic temperature of 115 °C showed that a popcorn bag released 150 ± 46 ng/g of 6:2 FTOH within 2 min, highlighting the potential for human exposure to volatile PFAS via inhalation or ingestion through migration into food. Overall, DTD-GC-MS provides a rapid, solvent-free approach for screening volatile PFAS and identifying SCFPs in food contact materials.