Analysis of neutral per- and polyfluoroalkyl substances (PFAS) by gas chromatography ‒ high resolution mass spectrometry (GC HRMS)

Most of the studies on per- and polyfluoroalkyl substances (PFAS) to date encompass water soluble and ionic PFAS analyzed by liquid chromatography ̶ mass spectrometry, yet analytical methods and information on the occurrence of neutral PFAS are lacking. To this aim, we developed a new method for analysis of forty neutral PFAS using gas chromatography (GC) ̶ Orbitrap mass spectrometry with electron ionization (EI). Analytes were comprised of 29 fluorotelomer alcohols, 6 fluorotelomer acrylates and methacrylates, 3 perfluoroalkane sulfonamides and 2 perfluoroalkane sulfonamido alcohols. Gas chromatographic separation was developed on two GC phases: a standard non-polar (5 % diphenyl and 95 % dimethyl polysiloxane) and a mid-polar (6 % cyanopropylphenyl, 94 % dimethylpolysiloxane). A custom-made high-resolution mass spectral (HRMS) library was developed and used to evaluate PFAS accuracy of identification. Overall, 85 % of PFAS were correctly identified. A quantitative method was developed and evaluated for sensitivity, linearity, reproducibility, and ion interferences. Method sensitivity varied for different PFAS from 1 to 50 ppb based on the lowest calibrated levels. The developed method was utilized for analysis of PFAS in paper-based food contact materials after developing and evaluating the extraction protocol. Method applicability was demonstrated by analyzing paper-based food packaging samples, where 6:2 fluorotelomer alcohol was detected and measured at levels up to 351 ng/g. The developed GCHRMS method can be utilized for identification and measurement of neutral PFAS in various matrices, including food, dust, food contact materials, textiles and others.