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Clean Water Act Analytical Methods

CWA Analytical Methods for Per- and Polyfluorinated Alkyl Substances (PFAS)

EPA is developing new analytical methods to test for PFAS compounds in wastewater, as well as other environmental media.


As discussed in EPA’s PFAS Action Plan, there are hundreds of different PFAS chemicals of varying carbon chain lengths and different functional groups. Analyzing them in a comprehensive way has been a challenge that scientists at all levels of government are working to address. EPA has published methods to test for certain PFAS in drinking water and is continuing to work on methods for other matrices.

Methods Under Development

In collaboration with the U.S. Department of Defense, EPA is developing analytical methods to test for PFAS in wastewater as well as surface water, groundwater, leachate, soil, sediment, biosolids, and fish tissue. The following list of 40 PFAS are the subject of analytical method development. Method development includes single- and multi-laboratory testing. Following single-laboratory validation, which demonstrates proof of concept, a multi-laboratory validation will be conducted to further determine method viability. EPA anticipates that multi-laboratory validation for this method will be finalized in 2021.

List of analytes being tested and Chemical Abstract Service (CAS) numbers
Abbreviation Name – Acid/Neutral Form  CAS#
PFBA Perfluorobutanoic acid 375-22-4
PFPeA Perfluoropentanoic acid 2706-90-3
PFHxA Perfluorohexanoic acid 307-24-4
PFHpA Perfluoroheptanoic acid 375-85-9
PFOA Perfluorooctanoic acid 335-67-1
PFNA Perfluorononanoic acid 375-95-1
PFDA Perfluorodecanoic acid 335-76-2
PFUnA Perfluoroundecanoic acid 2058-94-8
PFDoA Perfluorododecanoic acid 307-55-1
PFTrDA Perfluorotridecanoic acid 72629-94-8
PFTA Perfluorotetradecanoic acid 376-06-7
PFBS Perfluorobutanesulfonic acid 375-73-5
PFPeS Perfluoropentanesulfonic acid 2706-91-4
PFHxS Perfluorohexanesulfonic acid 355-46-4
PFHpS Perfluoroheptanesulfonic acid 375-92-8
PFOS Perfluorooctanesulfonic acid 1763-23-1
PFNS Perfluorononanesulfonic acid 68259-12-1
PFDS Perfluorodecanesulfonic acid 335-77-3
PFDoS Perfluorododecanesulfonic acid 79780-39-5
4:2 FTS 4:2 fluorotelomersulfonic acid 757124-72-4
6:2 FTS 6:2 fluorotelomersulfonic acid 27619-97-2
8:2 FTS 8:2 fluorotelomersulfonic acid 39108-34-4
NMeFOSAA N-Methylperfluorooctanesulfonamidoacetic acid 2355-31-9 
NEtFOSAA N-Ethylperfluorooctanesulfonamidoacetic acid 2991-50-6
PFOSA Perfluorooctanesulfonamide 754-91-6
NMeFOSA N-Methylperfluorooctanesulfonamide 31506-32-8
NEtFOSA N-Ethylperfluorooctanesulfonamide 4151-50-2
NMeFOSE N-Methylperfluorooctanesulfonamidoethanol 24448-09-7
NEtFOSE N-Ethylperfluorooctanesulfonamidoethanol 1691-99-2
HFPO-DA Hexafluoropropylene oxide dimer acid 13252-13-6
DONA 4,8-dioxa-3H-perfluorononanoic acid 919005-14-4
9Cl-PF3ONS 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid 756426-58-1
11Cl-PF3OUdS 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid 763051-92-9
3:3 FTCA 2H, 2H, 3H, 3H-perfluorohexanoic acid 356-02-5
5:3 FTCA 2H, 2H, 3H, 3H-perfluorooctanoic acid 914637-49-3
7:3 FTCA 2H, 2H, 3H, 3H-perfluorodecanoic acid 812-70-4
NFDHA Perfluoro-3,6-dioxaheptanoic acid 151772-58-6
PFEESA Perfluoro(2-ethoxyethane)sulfonic acid 113507-82-7
PFMPA Perfluoro-3-methoxypropanoic acid 377-73-1
PFMBA Perfluoro-4-methoxybutanoic acid 863090-89-5

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