PFAS · Sampling and Laboratory Data
What Is EPA Method 1621?
EPA Method 1621 estimates adsorbable organic fluorine, or AOF, in water samples. It captures organofluorine on granular carbon. It then measures fluorine by combustion ion chromatography.
AOF is an aggregate measurement. It can include fluorine from PFAS and from some non-PFAS fluorinated compounds, such as certain pesticides or pharmaceuticals. It does not identify individual PFAS. It also does not capture every possible organofluorine equally.
Method 1633A and AOF data answer different questions. AOF may show more organic fluorine than the target PFAS explain. The two numbers are not the same type of result. Follow the lab and agency review plan.
Keep the units and chemical basis visible. Target PFAS results give the mass of each compound. AOF gives fluorine caught by the method. Do not simply add the 40 targets and subtract them from AOF. The units and basis need proper conversion and expert review. Use the two tests as related evidence, not equal totals.
Key point: Method 1621 is a broad indicator, not a list of specific PFAS concentrations.
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PFAS in Wastewater: Sources, Sampling, Source Control, and Residuals
This page comes from the course. It covers PFAS sources in the sewershed, how PFAS moves through a treatment plant, sampling and lab methods, source control, treatment residuals and biosolids, one step at a time, with short knowledge checks and a certificate of completion.
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