Non-extractable PFAS in functional textiles - characterization by complementary methods: oxidation, hydrolysis, and fluorine sum parameters.

Per- and polyfluoroalkyl substances (PFAS) are widely used for durable water-repellent finishing of different fabrics and textiles such as outdoor clothing, carpets, medical textiles and more. Existing PFAS extraction techniques followed by target analysis are often insufficient for detecting widely used side-chain fluorinated polymers (SFPs) that are barely or non-extractable. SFPs are typically copolymers consisting of a non-fluorinated backbone with perfluoroalkyl side-chains to obtain desired properties. We compared the accessible analytical information and performance of complementary techniques based on oxidation (dTOP and PhotoTOP assays), hydrolysis (THP assay), standard extraction, extractable organic fluorine (EOF), and total fluorine (TF) with five functional textiles and characterized 7 further textiles only by PhotoTOP oxidation. The results show that when applied directly to textile samples, dTOP and PhotoTOP oxidation and also hydrolysis (THP) are able to capture large fractions of TF in the form of perfluoroalkyl side-chains present in the textiles while methods relying on extracts (EOF, target and non-target analysis) yield much lower fractions of TF (e.g., factor ∼25-50 lower). The conversion of large fractions of the measured TF into PFCAs or FTOHs from fluorinated side chains is in contrast to previous studies. Concentrations ranged from

PhotoTOP: PFAS Precursor Characterization by UV/TiO2 Photocatalysis.

To unravel the complexity of per- and polyfluoroalkyl substances (PFAS) in products and environmental samples, sum parameters that provide relevant information on chemical characteristics are necessary since not all PFAS can be captured by target analysis in case of missing reference standards or if they are not extractable or amenable to the analytical method. Therefore, we evaluated photocatalysis (UV/TiO2) as a further total oxidizable precursor approach (PhotoTOP) to characterize perfluoroalkyl acid precursors via their conversion to perfluoroalkyl carboxylic acids (PFCAs). Photocatalysis has the advantage that no salts are needed, allowing direct injection with liquid chromatography-mass spectrometry without time-consuming and potentially discriminating sample cleanup. OH radicals were monitored with OH probes to determine the reactivity. For eight different precursors (diPAPs, FTSAs, FTCAs, N-EtFOSAA, PFOSA), mass balance was achieved within 4 h of oxidation, and also, in the presence of matrix, complete conversion was possible. The PhotoTOP was able to predict the precursor chain length of known and here newly identified precursors qualitatively when applied to two PFAS-coated paper samples and technical PFAS mixtures. The length of the perfluorinated carbon chain (n) was mostly conserved in the form of PFCAs (n-1) with only minor fractions of shorter-chain PFCAs. Finally, an unknown fabric sample and a polymer mixture (no PFAS detectable in extracts) were oxidized, and the generated PFCAs indicated the occurrence of side-chain fluorinated polymers.