EPA method 537.1: a reference for the analysis of PFAS in drinking water

Jan 7, 2025 | Analytical standards 

U.S. EPA 537.1

EPA method 537.1, developed by the US Environmental Protection Agency, is a reference method for the determination of perfluoroalkyl and polyfluoroalkyl compounds (PFAS) in drinking water. This method was designed to meet the growing environmental monitoring requirements for these emerging contaminants, which are recognised for their persistence, mobility and potential toxicity.

Objective and principle of the method

EPA method 537.1 is based on solid phase extraction (SPE), followed by analysis using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). It enables the precise detection and quantification of a specific set of 18 PFAS in drinking water matrices, including groundwater, surface water intended for human consumption and treated water.

List of compounds targeted by EPA 537.1

This method can be used to monitor the following compounds (analyte, acronym, Chemical Abstract Services – CAS):

  • Hexafluoropropylene oxide dimer acid, HFPO-DA, 13252-13-6.
  • N-ethyl perfluorooctanesulfonamidoacetic acid, NEtFOSAA, 2991-50-6.
  • N-methyl perfluorooctanesulfonamidoacetic acid, NMeFOSAA, 2355-31-9.
  • Perfluorobutanesulfonic acid, PFBS, 375-73-5.
  • Perfluorodecanoic acid, PFDA, 335-76-2.
  • Perfluorododecanoic acid, PFDoA, 307-55-1.
  • Perfluoroheptanoic acid, PFHpA, 375-85-9.
  • Perfluorohexanesulfonic acid, PFHxS, 355-46-4.
  • Perfluorohexanoic acid, PFHxA, 307-24-4.
  • Perfluorononanoic acid, PFNA, 375-95-1.
  • Perfluorooctanesulfonic acid, PFOS, 1763-23-1.
  • Perfluorooctanoic acid, PFOA, 335-67-1.
  • Perfluorotetradecanoic acid, PFTA, 376-06-7.
  • Perfluorotridecanoic acid, PFTrDA, 72629-94-8.
  • Perfluoroundecanoic acid, PFUnA, 2058-94-8.
  • 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid, 11Cl-PF3OUdS, 763051-92-9 (salt) / 83329-89-9 (potassium).
  • 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acid, 9Cl-PF3ONS, 756426-58-1 (salt) / 73606-19-6 (potassium).
  • 4,8-dioxa-3H-perfluorononanoic acid, ADONA, 919005-14-4 ( sodium salt) / 958445-44-8 (ammonium).

Internal standards used for quantification:

  • Perfluoro-[1,2-¹³C₂]octanoic acid, 13C2-PFOA.
  • Sodium perfluoro-1-[1,2,3,4-¹³C₄]octanesulfonate, 13C4-PFOS.
  • N-Deuteromethylperfluoro-1-octanesulfonamidoacetic acid, d3-NMeFOSAA.

Surrogates added to monitor analytical performance:

  • Perfluoro-n-[1,2-¹³C₂]hexanoic acid, 13C2-PFHxA.
  • Perfluoro-n-[1,2-¹³C₂]decanoic acid, 13C2-PFDA.
  • N-Deuterioethylperfluoro-1-octanesulfonamidoacetic acid, d5-NEtFOSAA.
  • Tetrafluoro-2-heptafluoropropoxy-¹³C₃-propanoic acid, 13C3-HFPO-DA.

source : EPA Method 537.1 – Revision 2.0 (March 2020) – Document n° EPA/600/R-20/006
Full title: Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

Our solutions for implementing the method

To meet the needs of laboratories implementing EPA method 537.1, Wellington Laboratories have developed a complete range of analytical standards compatible with this method.

Here are a few examples:

EPA-537SS-R1

Alternative standards (Surrogates – SUR)

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The EPA-537SS-R1 mixture contains 4 isotopically labelled compounds, covering the main functional families and solubility ranges:

  • Perfluoro-n-[1,2-13C2]hexanoic acid, ¹³C₂-PFHxA.
  • Perfluoro-n-[1,2-13C2]decanoic acid, ¹³C₂-PFDA.
  • N-deuterioethylperfluoro-1-octanesulfonamidoacetic acid, d₅-NEtFOSAA.
  • Tetrafluoro-2-heptafluoropropoxy-13C3-propanoic acid, ¹³C₃-HFPO-DA.

These surrogates are added to the field and QC samples to check extraction yields.

EPA-537IS

Internal standards

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The EPA-537IS mixture contains 3 isotopically labelled compounds corresponding to the target analytes:

  • Perfluoro-n-[1,2-13C2]hexanoic acid, ¹³C₂-PFOA.
  • Sodium perfluoro-1-[1,2,3,4-13C4]octanesulfonate, ¹³C₄-PFOS.
  • N-Deuteromethylperfluoro-1-octanesulfonamidoacetic acid, d₃-NMeFOSAA.

These standards are used for quantification by internal calibration.

EPA-537PDSL-R1

Native standards targeted by the method

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See also:

EPA-537APDS

Native standards targeted by the method + linear and branched isomers of PFOA and PFNA

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The EPA-537PDSL-R1 mixture contains the 18 native analytes recommended for calibration and verification of analytical performance according to the EPA method:

  • 9 linear perfluoroalkyl carboxylic acids (PFCAs):
    • Perfluorohexanoic acid, PFHxA.
    • Perfluoroheptanoic acid, PFHpA.
    • Perfluorooctanoic acid, PFOA.
    • Perfluorononanoic acid, PFNA.
    • Perfluorodecanoic acid, PFDA.
    • Perfluoroundecanoic acid, PFUdA.
    • Perfluorododecanoic acid, PFDoA.
    • Perfluorotridecanoic acid, PFTrDA.
    • Perfluorotetradecanoic acid, PFTeDA.
  • 3 linear perfluoroalkyl sulfonic acids (PFSAs):
    • Perfluorobutanesulfonic acid (potassium salt), L-PFBS.
    • Perfluorohexanesulfonic acid (sodium salt), L-PFHxS.
    • Perfluorooctanesulfonic acid (sodium salt), L-PFOS.
  • 2 N-substituted sulfonamidoacetic acids:
    • N-Methylperfluoro-1-octanesulfonamidoacetic acid, N-MeFOSAA.
    • N-ethylperfluoro-1-octanesulfonamidoacetic acid, N-EtFOSAA.
  • 3 additional compounds:
    • Hexafluoropropylene oxide dimer acid, HFPO-DA (GenX).
    • 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (potassium salt), 9Cl-PF3ONS.
    • 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (potassium salt), 11Cl-PF3OUdS.
    • 4,8-dioxa-3H-perfluorononanoic acid (sodium salt), NaDONA (ADONA).

 

Why use Wellington standards?

  • Direct compatibility with EPA methods (537.1, 533, etc.).
  • Guaranteed purity and traceability of standards.
  • Ready-to-use formulations, optimising analytical performance.
  • ISO 9001-compliant development.

EPA method 537.1 has established itself as an essential analytical tool for monitoring PFAS in drinking water. Thanks to the calibrated mixtures offered by Wellington Laboratories, laboratories have access to solutions tailored to meet current regulatory and scientific requirements. These tools form an essential foundation for any rigorous control strategy for PFAS in the environment.

Find out more:

EPA-533APDS-PFAS-mélange-Wellington_France

We can help you:

BCP Instruments puts its expertise at the service of French and Belgian laboratories to help you with your environmental analyses. Contact us today to find out how our solutions can meet your specific needs.