Advancing the Detection of poly- & perfluorinated hydrocarbons in the Environment using GC-MS and GC×GC-MS

Introduction Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a family of manufactured chemicals that are widely employed in consumer goods and industrial applications because of their special qualities. Chemically, these compounds contain a chain of carbon atoms bonded to multiple fluorine atoms, and with different functional groups at the end of the chain. A portion of these chemicals exhibit a neutral and volatile nature, and are recently gaining more attention from environmental agencies, since they can be released by consumer goods and accumulate in the environment. Even at molecular weights over 600 Da, the presence of fluorine atoms in PFAS makes them more volatile than non-fluorinated analogues, due to weak van der Waals interaction properties. Therefore, they are suitable for GC-MS analysis. Materials and Methods In the current research, a parallel GC and GC×GC methodology coupled with both low-resolution and high-resolution TOF MS was developed for the (semi)volatile PFAS analysis. Specifically, the chemical group under study were fluorotelomer alcohols (FTOH), acrylates (FTAc), and alkyl sulfonamide (N-MeFOSA, N-EtFOSA, N-MeFOSE, and N-EtFOSE) derivatives. Regarding the MS ion source, both electron impact, positive chemical ionization, and negative chemical ionization were exploited to study the spectra of the targeted chemical groups. Dynamic headspace extraction was used for sampling, using the most appropriate adsorbent material in terms of selectivity and sensitivity. Initially, the extraction method was optimized in terms of sampling volume and adsorbent type using a mix of PFAS standards (MW range 264-571 Da) with various environmental samples (water, soil). Electron ionization (EI), positive chemical ionization (PCI), and negative chemical ionization (NCI) modes were employed to elucidate their fragmentation patterns and ionization behavior. Results The method was optimized and validated for nine target PFAS, including fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTAc), and alkyl sulfonamides (FOSA, FOSE). Three adsorbent materials—Tenax TA, Carbotrap T420, and Carbotrap 202—as well as three extraction volumes (1 L, 2 L, and 5 L) were evaluated. Among these, Tenax TA showed the best performance in terms of recovery and repeatability, while the 1 L extraction volume provided the most consistent and reliable results. The final methodology was refined for both soil and water samples, allowing LODs ranging from 2.2 to 490 ppt, with an average accuracy and precision of 101% and 5.4%, respectively. Discussion and Conclusion A novel sensitive 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.