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.
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 in non-potable water and continues to work on methods for other matrices.
Office of Water, in partnership with the Department of Defense’s (DoD) Strategic Environmental Research and Development Program, has published draft Method 1633, a single-laboratory validated method to test for 40 PFAS compounds in wastewater, surface water, groundwater, soil, biosolids, sediment, landfill leachate, and fish tissue. This draft method can be used in various applications, including National Pollutant Discharge Elimination System (NPDES) permits. The method will support NPDES implementation by providing a consistent PFAS method that has been tested in a wide variety of wastewaters and contains all the required quality control procedures for the CWA. While the method is not nationally required for CWA compliance monitoring until EPA has promulgated it through rulemaking, it is recommended now for use in individual permits.
Historically, EPA published draft methods on this Clean Water Act Methods website after completing the single-laboratory validation report. However, due to many public and stakeholder requests, this method was made available while DoD and EPA prepared the single-laboratory validation study report. The report is now available below.
Multiple EPA programs have reviewed this draft method. DoD has begun a multi-laboratory validation study of the procedure, which is expected to be completed in 2022. DoD's multi-laboratory validation is proceeding in collaboration with the Office of Water, the Office of Land and Emergency Management, and the Office of Research and Development.
The Office of Water will use the results of the multi-laboratory validation study to finalize the method and add formal performance criteria. The method validation process may eliminate some of the parameters listed in this draft method.
In the meantime, the Office of Water encourages laboratories, regulatory authorities, and other interested parties to review and use the draft method, with the understanding that it is subject to revision.
EPA is grateful for the constructive feedback received from multiple interested parties to date, which resulted in the second draft of the method provided below. If stakeholders identify additional areas that need clarification, further revisions will be made.
EPA’s Office of Water has published Draft Method 1621, “Screening Method for the Determination of Adsorbable Organic Fluorine (AOF) in Aqueous Matrices by Combustion Ion Chromatography (CIC),” a single-laboratory validated method to screen for organofluorines in wastewater. This method detects organofluorines (molecules with a carbon-fluorine bond), which are rarely naturally occurring. The most common sources of organofluorines are PFAS and non-PFAS fluorinated compounds such as pesticides and pharmaceuticals.
The method is labeled as a screening method because it does not quantify all organofluorines with the same accuracy and has some known interferences that are discussed in the first section of the method. The method tells the user that the organofluorines are present, but does not identify which organofluorines are present. The strength of the method is that it can broadly screen for thousands of known PFAS compounds at the part per billion level in aqueous (water) samples.
EPA’s new Draft Method 1621 has completed single-laboratory validation. Multi-laboratory validation will take place this summer. The Office of Water will use the results of the multi-laboratory validation study to finalize the method and add formal performance criteria. In the meantime, the Office of Water encourages interested parties to review and use the method, with the understanding that it is subject to revision and is not nationally required for CWA compliance monitoring until it has been promulgated through rulemaking.