Exploiting GC(×GC)-HRMS capabilities for targeted and non-targeted analysis of (semi)volatile poly- & perfluorinated hydrocarbons in environmental samples

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. 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. 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 (FOSAs and FOSEs) 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 air sampling, using the most appropriate adsorbent material in terms of selectivity and sensitivity. The use of multiple ionization forms combined with HRMS allowed for high-level information of the target compounds, allowing both fragments fingerprinting and molecular ion presence, useful for the generation of a dedicated mass spectral library. The developed approach, including the dynamic headspace extraction, the GC(×GC) separation, and the HRMS combines high-sensitivity and high-resolution for both confirmatory and exploratory analysis of known and unknown PFAS in environmental samples. The growing concerns regarding the (semi)volatile PFAS make the approach and research insights highly relevant for their characterization and determination.