Determination and chemical characterization of per- and polyfluoroalkyl substances using one- and two-dimensional gas chromatography coupled with low- and high-resolution time-offlight mass spectrometry

Per- and polyfluoroalkyl substances (PFAS) comprise a large group of synthetic compounds extensively used in industrial processes and consumer products since the 1930s, owing to their exceptional chemical and thermal stability derived from strong carbon-fluorine bonds. Their amphiphilic structure, combining a fluorinated hydrophobic alkyl chain with a polar functional group, confers surfactant properties while also contributing to their environmental persistence and bioaccumulative behavior, raising health and ecological concerns. Despite their relatively high molecular masses (often exceeding 600 Da), many PFAS exhibit a certain volatility which makes them suitable for their determination by gas chromatography coupled with mass spectrometry (GC-MS). In thisstudy, a dual analytical approach is presented, combining one-dimensional gas chromatography and comprehensive two-dimensional gas chromatography (GC×GC) coupled with both low- and high-resolution time-of-flight mass spectrometry (TOFMS) for the detection and characterization of (semi)volatile PFAS. The method targeted four main subclasses: fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTAc), and sulfonamide-based derivatives (N-MeFOSA, N-EtFOSA, N-MeFOSE, and N-EtFOSE). Electron ionization (EI), positive chemical ionization (PCI), and negative chemical ionization (NCI) modes were employed to elucidate their fragmentation patterns and ionization behavior. A novel workflow was implemented for the extraction and analysis of PFAS from environmental matrices, combining dynamic headspace (DHS) extraction with thermal desorption (TD) tubes and GC×GC-TOFMS. This strategy provides a robust platform for both targeted quantification and untargeted screening of fluorinated contaminants. The applicability of the approach is demonstrated and validated on soil samples.