EPA 1633 Method Reaches Final Stage with Successful Validation

SGS, the leading expert in PFAS analysis, has successfully completed the multi-laboratory validation of the EPA 1633 method, marking a significant milestone for both the company and the entire environmental testing industry. This accomplishment solidifies EPA 1633 as the comprehensive reference method for analyzing PFAS in non-potable aqueous, solid and tissue samples.

The successful validation demonstrates that the EPA 1633 method, developed by SGS, is robust and can be effectively performed across multiple laboratories, ensuring reliability and consistency in testing results.

The finalization of the EPA 1633 method brings several important updates and benefits.

Finalized specifications

The method specifications for solids and tissues have been finalized, complementing the previously completed specifications for aqueous samples outlined in Draft 4. This ensures consistency and clarity in testing protocols, giving confidence in the accuracy of results.

Accreditation updates

Although the final version of EPA 1633 now supersedes all previous versions, the process of updating accreditations to align with this standard will take time. SGS is proactively leading this effort, with our Orlando and SGS AXYS Sidney, BC laboratories already updating their accreditations to EPA 1633. The Dayton laboratory is expected to follow in the next quarter. Major data users, including the US Department of Defense, have recognized the minor differences and are providing flexibility in the accreditation transition process, allowing ample time for compliance.

Streamlined processes

For National Pollutant Discharge Elimination System (NPDES) permitting purposes, the requirement for laboratory duplicates has been eliminated, simplifying the testing process without sacrificing accuracy. Additionally, consistent with other isotope dilution 1600 series methods, MS/MSDs are no longer required, further streamlining laboratory operations.

Key updates following the finalization

After the finalization of the EPA 1633 method, several procedural updates and increased performance-based flexibilities have been introduced:

• Enhanced sample handling: the method now allows for aqueous samples with higher than 50 mg solids, offering flexibility based on prior approval to centrifuge the sample, decant the aqueous phase, and report as two separate samples. Either a visual examination or a Total Suspended Solids (TSS) analysis is acceptable
• Improved cleanup procedures: the method now incorporates the use of carbon cartridges for extract cleanup, building on earlier draft versions
• EIS recovery floor established: a minimum recovery floor of 5% has been set for Extraction Internal Standard (EIS) recovery. Data below this threshold will be reported as an estimated value
• Instrument sensitivity checks: sensitivity checks are now required at the beginning of each analytical sequence, ensuring consistent instrument performance
• Extended holding times for tissues: for tissue samples, if they are frozen within 48 hours of collection, the holding time now begins only when processing starts, not at the time of collection
• Flexible dilution processes: the method now includes an explicit dilution factor (DF) in calculations and specifies that dilutions can be performed only for analytes exceeding the range. The previous requirement to limit dilution to a 10X factor has been removed, as long as EIS recoveries meet signal and retention time criteria

SGS remains committed to providing industry-leading environmental testing services, and the finalization of the EPA 1633 method is a testament to our dedication to excellence and innovation in PFAS analysis.