SW-846 Update VII Announcements
EPA released Update VII to the SW-846 compendium of methods.
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EPA finalized changes to the hazardous waste regulations that modernize how the hazardous waste characteristic of ignitability is determined under the Resource Conservation and Recovery Act. These amendments allow for the use of modern equipment and techniques for making ignitability determinations for waste. The final rulemaking also allows the use of non-mercury thermometers in a variety of EPA’s analytical methods that currently require mercury thermometers. These changes reduce potential mercury exposures to humans and the environment by reducing the overall use of mercury-containing products.
EPA sought input on the proposal in a 60-day public comment period that ended on June 3, 2019. EPA carefully considered all the comments before issuing the final rulemaking, which was signed on June 8, 2020.
- View the official copy of the proposed rule in the Federal Register; and
- For more information and to view the official copy of the final rule in the Federal Register, check out the Modernizing Ignitable Liquids Determinations Final Rule web page.
SW-846 Methods 3512 and 8327 were validated together for 24 Per- and Polyfluoroalkyl Substances (PFAS) in surface water, groundwater, and wastewater, and final versions were published in the SW-846 Compendium on July 30, 2021 and are available for use:
Method 3512 is a rapid preparation method for non-potable waters wherein samples are diluted (1:1) with a water-miscible organic solvent (methanol), mixed, filtered through a particle filter (0.2 µm), and adjusted with acetic acid (0.1% by volume) prior to determinative analysis.
Method 8327 is used for determination of selected PFAS in prepared samples or sample extracts using liquid chromatography/tandem mass spectrometry (LC/MS/MS). A liquid chromatography column with a ~2 µm particle size stationary phase provides exceptional chromatographic resolution, and tandem mass spectrometry (MS/MS) provides a high degree of specificity and sensitivity. This method was validated using negative electrospray ionization and external standard calibration.
1. Method 8327, “Per- and Polyfluoroalkyl Substances by Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)”, is published as an external standard calibration method. Is isotope dilution calibration permitted to be used for quantitative analysis?
Method 8327 was validated as an external standard calibration method. The Methods Innovation Rule identifies SW-846 methods for non-Method Defined Parameters, including Method 8327, as guidance. Appropriate modifications may be made to these methods, including the use of an alternate calibration model, as long as the laboratory demonstrates it can generate data of appropriate quality for the intended application and the modifications are acceptable and transparent to the end data user (e.g., regulatory authority). Please refer to Section 9.0 for categories of quality controls and associated acceptance criteria, and refer to the client or end data user for project-specific Data Quality Objectives.
Note: The preparation and analysis method modifications that would be needed to support the use of isotope dilution/extracted internal standard calibration are not explicitly identified in either method. SW-846 Method 8000D provides some details about these calibration models. A laboratory should document all method modifications and provide to the end data user for their consideration.
2. SW-846 Method 8327, “Per- and Polyfluoroalkyl Substances (PFAS) by Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS),” provides a recommended maximum holding time for aqueous samples to be used as a guideline. Why did EPA not specify a required maximum holding time?
At the time Method 8327 was published, EPA had not completed a formal holding time study in non-potable water samples for the target analytes included in the method. Section 8.2 of Method 8327 recommends a maximum holding time of 14 days from sample collection to preparation and refrigerated (0-6ºC) storage as a guideline, and it recommends frozen storage to extend holding times beyond 14 days. These recommendations may be updated once a formal holding time study is published.
Chapter 4 of SW-846 which contains a table with recommended containers, preservations, and holding times for organic analytes, does not directly address PFAS, but it does state that sample handling and preservation guidelines are intended to maintain sample integrity and improve stability of organic chemicals in the sample matrix between collection and laboratory preparation and analysis. EPA intends to add PFAS-related information to a future revision of Chapter 4, including recommended sample containers, preservation and holding times.