Analysis and Quantitation of Polyfluorinated Alkyl Substances (PFAS) in EPA Method 537.1 Using High Resolution Accurate Mass Spectrometry

Characterization of Polyfluoroalkyl Substances in the Environment
Poster Presentation

Prepared by , C. Gilles, E. Wang, J. Byrne II, Y. Fujito

Contact Information: brprakash@shimadzu.com; 410-910-0903


ABSTRACT

EPA Method 537 was recently expanded to EPA Method 537.1 in November 2018 to include four new per-/polyfluoroalkyl substances (PFAS) compounds including GenX. While EPA Method 537.1 focuses on well-known PFAS, there are thousands of unknown PFAS that can potentially contaminate drinking water. Analysis of unknown contaminants requires high resolution and accurate mass capabilities in order to positively identify the molecular formula. This poster demonstrates that the quantitation of all compounds in EPA Method 537.1 can be performed on a quadrupole time-of-flight mass spectrometer (QTOF) at low parts per trillion concentrations in environmental drinking water samples. Quantitation limits on the QTOF are compared to a triple quadrupole mass spectrometer (QQQ).
ESI source conditions were optimized on a QQQ and applied to the QTOF. MRM transitions were determined on a QQQ, and accurate mass precursor/product ions were determined on a QTOF. The chromatographic parameters are based on the chromatographic method used in EPA Method 537.1. A Shim-pack XR-ODS 50 x 3.0 mm column was used as a delay column, and a Restek Raptor C18 150 x 2.1 mm column was used as the analytical column. Quantitation was performed using MRM on the QQQ and high-resolution MRM on the QTOF.
Both instruments showed linearity with average regression coefficients greater than 0.99 for most analytes. Calibration curves for all analytes were found to be linear from 5-400 ppt for a 250 mL sample extract. A precision and accuracy study was performed on all compounds. The Method Detection Limit was calculated as described in 40 CFR Part 136 Appendix B