Modified EPA Method 533 for Analysis of PFAS in Drinking Water and Source Water

Drinking Water
Oral Presentation

Prepared by Y. Li, J. Whitaker
Eurofins Eaton Analytical, LLC, 110 South Hill Street, South Bend, IN, 46617, United States

Contact Information: [email protected]; 574-472-5562


Human exposure to per- and polyfluoroalkyl substances (PFAS) has become a worldwide public health issue. Reports have estimated that over 3,000 PFAS exist on the global market, used in a wide variety of industrial and consumer applications. The industry has introduced shorter chain PFAS as an alternative to the legacy long-chain PFAS. In order to respond to the increasing PFAS concerns, the U.S. EPA implemented the third Unregulated Contaminant Monitoring Rule (UCMR3) for the assessment monitoring of 6 selected PFAS during 2013-2015 and established the drinking water lifetime health advisories of 70 ng/L for PFOA/PFOS in 2016. The pace of action on PFAS issues varies greatly from state to state. Several states have established, recommended, or proposed maximum contaminant levels, notification levels, human health-based values, trigger levels, or action levels. Other states have also developed statewide action plans. In the recently proposed UCMR5, EPA Methods 537.1 (Revision 2.0) and 533 are specified for the assessment monitoring of 29 PFAS during 2023-2025.

EPA Method 537.1, evolved from the original EPA Method 537, is a LC/MS/MS method combined with reversed-phase solid-phase extraction (SPE), which was validated for 18 PFAS using internal standards. The recently published EPA Method 533 is a LC/MS/MS method combined with a weak anion exchange (WAX) SPE, which was validated for 25 PFAS using isotope dilution analogues (IDA). Unlike reversed-phase SPE, WAX SPE is effective for extracting more polar and shorter-chain PFAS, but may be challenged for extracting less polar and longer-chain PFAS, particularly for nonionic PFAS. Because LC/MS/MS is sophisticated and expensive, it is more efficient to use fewer LC/MS/MS methods for PFAS analyses.

The ultimate purpose of this study was to develop one single and cost-effective LC/MS/MS method capable of analyzing a comprehensive list of PFAS in drinking water and source water. The preliminary data indicate that 53 PFAS can be analyzed by the modifed EPA Method 533 with passing QC acceptance criteria as specified in the EPA methods for all 29 UCMR5 PFAS plus nearly two dozen other PFAS. This presentation will be highlighted with: 1) optimization of the modified EPA Method 533 LC/MS/MS and SPE conditions, 2) initial demonstration of capability for drinking water analysis, 3) demonstration of capability for source water analysis, and 4) discussion of potential challenges and solutions for drinking water and source water analyses.