Detection, quantification, and isomer differentiation of per- and polyfluoroalkyl substances (PFAS) using MALDI-TOF with trapped ion mobility

Per- and polyfluoroalkyl substances (PFAS) are a class of organic compounds that have attracted global attention for their persistence in the environment, exposure to biological organisms, and their adverse health effects. There is an urgent need to develop analytical methodologies for characterization of PFAS in various sample matrices. In the present study, a list of legacy and alternative perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs) was analyzed by matrix-assisted laser/desorption ionization time-of-flight mass spectrometry coupled with trapped ion mobility spectrometry (MALDI-TIMS-TOF). Parts per billion (ppb) quantitation and detection was achieved for PFCAs whereas PFSAs yielded parts per trillion (ppt) quantitation and detection. Multi-day calibration curves were assessed by linear regression and calculation of limits of detection and quantification. Using TIMS, we also successfully separated three perfluorooctanesulfonic acid (PFOS) structure isomers in the gas phase. Our results demonstrated the new development of utilizing MALDI-TOF-MS coupled with TIMS for fast, quantitative, and sensitive analysis of PFAS, paving ways to future high-throughput and in situ analysis of PFAS such as MS imaging applications.