Synthesis, purification and characterisation of novel PFAS following nontarget analysis

PFAS, or per- and polyfluorinated alkyl substances, are among the most prevalent environmental contaminants. Because of their toxicity and widespread use, these substances must be regulated in order to reduce the associated hazards. Effective regulation requires accurate measurement of PFAS concentrations, but the lack of commercially available reference standards hinders the identification and quantification of novel PFAS discovered through nontarget analysis techniques. In this work, we aimed to fill this gap by synthetising new PFAS reference standards, based on findings reported in the literature through nontarget assays.

We performed the synthesis of 17 novel PFAS reference standards, including three fluorotelomer thioether amido sulfonic acid (FTSASs), three fluorotelomer sulfonyl amido sulfonic acid (FtSO2AoS), 6:2 Fluorotelomer sulfinyl amido sulfonic acid (6:2 FtSOAo), three perfluoroalkane sulfonamide diacetic acids (FASEE diacids), three perfluroalkyl amidoalkyl amine (PFAAAm), perfluoro (4-methyl-3,6-dioxaoct-7-ene) sodium sulfonate (PS acid sodium salt), perfluoro (4-methyl-3,6-dioxaoct-7-ene) sulfonic acid (PS acid), perfluoro-3-{ [1-(ethenyloxy)propan-2-yl]oxy}propanoic acid (EVE acid), and 6- (2,2,3,3,4,4,4-Heptafluorobutoxy)hexan-1-ol. Various chemical reactions were carried out to synthesise the chemicals, and the Dry Column Vacuum Chromatography (DCVC) was selected as the best purification technique. The linear isomer product was obtained by recrystallisation when branched isomers were present. The identity and purity of the synthesised reference standards were confirmed using a combination of NMR spectroscopy (¹H, ¹⁹F, ¹³C) and mass spectrometry (m/z, LC-MS, or GC–MS).