Date: January 21, 2025
EPA published a proposal to add Method 1633A for 40 PFAS, Method 1621 for adsorbable organic fluorine, and Method 1628 for PCB congeners to 40 CFR Part 136, and to withdraw several Aroclor methods. The comment period closed March 24, 2025, and the rule was still listed as proposed in October 2026.
What it means for calibration
If the rule is finalized, Method 1633A becomes an approved Clean Water Act method for PFAS in wastewater. Permit labs would need initial calibrations that hold up at very low concentrations across 40 analytes, and each analyte’s curve is its own model decision.
Source: www.epa.gov
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