Merit Laboratories was just one of four national laboratories acknowledged in the newest approved method, EPA 533, for PFAS testing in drinking water that just released by the U.S. EPA. Merit was acknowledged in the approved method for completing a validation study using EPA 533 and was recognized for providing valuable feedback on the method procedures and reviewing the draft method manuscript.

EPA 533 is a solid phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of select per- and polyfluoroalkyl substances (PFAS) in drinking water. Isotope dilution is incorporated into the method, which can minimize sample matrix interference and improve data quality.

EPA 533 requires the use of MS/MS in Multiple Reaction Monitoring (MRM) mode to enhance selectivity. The method states that EPA 533 is intended for use by analysts skilled in the performance of solid phase extractions, the operation of LC-MS/MS instrumentation, and the interpretation of the associated data.

According to the published method, EPA 533 “may support a variety of monitoring applications, which include the analysis of multiple short-chain per- and polyfluoroalkyl substances (PFAS) that cannot be measured by Method 537.1.”  The release of Method 533 helps the EPA satisfy a commitment specified in the PFAS Action Plan to develop new validated methods to accurately test for additional PFAS in drinking water. Method 533 incorporates isotope dilution, which can minimize sample matrix interference and improve data quality. 

The analyte list identified in EPA Method 533 for laboratory testing in drinking water include:

• 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)

• 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acd (9Cl-PF3ONS)

• 4,8-Dioxa-3H-perfluorononanoic acid (ADONA )

• Hexafluoropropylene oxide dimer acid (HFPO-DA)

• Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)

• Perfluorobutanoic acid (PFBA)

• Perfluorobutanesulfonic acid (PFBS)

• 1H,1H, 2H, 2H-Perfluorodecane sulfonic acid (8:2FTS)

• Perfluorodecanoic acid (PFDA)

• Perfluorododecanoic acid (PFDoA)

• Perfluoro(2-ethoxyethane)sulfonic acid (PFEESA)

• Perfluoroheptanesulfonic acid (PFHpS)

• Perfluoroheptanoic acid (PFHpA)

• 1H,1H, 2H, 2H-Perfluorohexane sulfonic acid (4:2FTS)

• Perfluorohexanesulfonic acid (PFHxS)

• Perfluorohexanoic acid (PFHxA)

• Perfluoro-3-methoxypropanoic acid (PFMPA)

• Perfluoro-4-methoxybutanoic acid (PFMBA)

• Perfluorononanoic acid (PFNA)

• 1H,1H, 2H, 2H-Perfluorooctane sulfonic acid (6:2FTS)

• Perfluorooctanesulfonic acid (PFOS)

• Perfluorooctanoic acid (PFOA)

• Perfluoropentanoic acid (PFPeA)

• Perfluoropentanesulfonic acid (PFPeS)

• Perfluoroundecanoic acid (PFUnA)

Merit is a leading PFAS environmental laboratory, analyzing drinking water, soil, wastewater, groundwater, and other sample matrices, including biosolids and sludge.  Merit is certified for the analysis of PFAS by ISO/IEC 17025. Analytical method certification for PFAS includes drinking water by EPA 537.1 and EPA 537 rev. 1.1 and soil, wastewater, groundwater, and surface water by ASTM D7979 with Isotopic Dilution. Please contact Merit Laboratories for assistance on your PFAS testing needs.