Analytical Methods for PFAS: Method 1633 & Method 1621

By Justin Pimpare, USEPA New England

The EPA has published two final analytical methods for PFAS: Method 1633 and Method 1621, fulfilling a commitment in its October 2021 PFAS Strategic Roadmap. These analytical methods will be used by laboratories to test samples for PFAS in a consistent and reliable way.

The agency collaborated closely with the Department of Defense to validate Method 1633, which measures 40 PFAS compounds and is suitable for use in various applications, including compliance monitoring. Method 1621 measures adsorbable organic fluorine in wastewater, a surrogate for measuring the total amount of PFAS, which will also help detect fluorine-containing pesticides and pharmaceuticals.

These methods are a significant step forward in efforts to identify what PFAS are present in environmental samples, and at what levels, enabling EPA, states and Tribes, wastewater facilities, and other entities to monitor a range of different effluents and media for PFAS, including under the National Pollutant Discharge Elimination System (NPDES) Program.

Before the publication of these methods, communities, NPDES permit authorities, and facilities relied on methods that were less rigorously tested, provided less consistency, and were not as widely available. With this action, EPA is providing methods for analyzing PFAS that have been tested in a variety of wastewaters. Method 1633 measures PFAS compounds in other matrices, too, including: surface water, ground water, biosolids, sediment, landfill leachate, soil, and fish tissue.

Both methods were developed in accordance with the required quality assurance and control procedures specified for EPA Clean Water Act methods in the Code of Federal Regulations. EPA encourages laboratories, regulatory authorities, and other interested parties to review and use these methods, and EPA recommends their use now in NPDES permits.

As a next step, EPA expects to propose both methods for adoption in the Code of Federal Regulations, a necessary step for them to be nationally required for Clean Water Act use. That formal promulgation process will include public comment.

Both methods and their multi-laboratory validation study reports are available on the Agency’s Clean Water Act Laboratory Methods website.

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