Development of a RPWAX×RPLC-HRMS platform for the nontargeted identification of pfass in aqueous film-forming foams

This research aims at the development of a novel 2D-LC method coupled to high-resolution mass spectrometry (HRMS) for the identification of anionic and zwitterionic poly- and perfluorinated compounds (PFASs) in fire-fighting aqueous-film forming foams (AFFFs), laying the groundwork for the analysis of these compounds in environmental matrices. In detail, the 2D-LC-HRMS method was developed by investigating the combination of mixed-mode weak anion exchange stationary phases with the traditional octadecyl reversed-phase, to obtain a separation in the two-dimensional space according to the anionic classes of PFAS and their chain length. The orthogonality studies and the optimization of the two-dimensional configuration were performed on a training set of twenty-four anionic PFASs, representing the main classes of compounds occurring in AFFFs and covering a wide range of physicochemical properties. The 2D-LC method development was carried out investigating full gradient setups in combination with active solvent and stationary phase assisted modulations. Furthermore, the 2D-LC-HRMS data from method development and sample analysis were processed using an on-purpose algorithm based on the Self-Adjusting Feature Detection, here implemented for the non-targeted feature detection in the two-dimensional space. Finally, the developed method was applied to the non-targeted analysis of two AFFF samples for the identification of homologous series of PFASs