Targeted and Non‐Targeted Analysis of Novel and Legacy Per and Polyfluoroalkyl Substances in River Water by Direct Analysis in Real Time Mass Spectrometry

RATIONALE: Because of their ubiquity in the environment and adverse health effects, per and polyfluoroalkyl substances (PFAS) are a growing area of concern to the public and regulatory agencies. The continued development of novel replacement PFAS necessitates the development of new methods to screen for these compounds. In this work, we demonstrate a method to detect multiple classes of PFAS including legacy PFAS, precursor compounds, and replacement compounds. METHODS: Compounds were adsorbed to octadecylamine then analyzed by direct analysis in real time (DART) coupled with time-of-flight (TOF) mass spectrometry. Sixteen PFAS were analyzed from six distinct classes including perfluorinated carboxylic acids (PFCAs), perfluorinated sulfonic acids (PFSAs), per and polyfluoroalkyl ether carboxylic acids (PFECAs), polyfluoroalkyl ether sulfonic acids (PolyFESAs), fluorotelomer alcohol (FTOH), and perfluorooctane sulfonamidoacetic acid (FOSAA). These represent the classes considered in EPA method 537.1 and an additional important precursor class. RESULTS: All six of the compound classes considered were successfully detected with this DART high resolution mass spectrometry (HRMS) method. Calculated lower limits of quantification ranged from 10 to 300 ng/L and were influenced by water matrix. The use of DART avoided instrumental background from solvents and tubing which is an established issue in liquid chromatography (LC) methods. DART-HRMS was also found to avoid false positives from compounds of similar molecular weights present in natural waters. CONCLUSIONS: The findings of this work fill an important gap in PFAS analysis by enabling screening for many known classes of PFAS. Furthermore, this method is anticipated to be able to analyze additional classes of PFAS as future replacement chemicals are produced, allowing for a more comprehensive analysis to be completed.