PFAS Analytical Chemistry: The Foundation of Treatment Assessment
Any discussion of PFAS treatment effectiveness depends on reliable analytical measurement of PFAS concentrations before and after treatment. Understanding the key analytical methods—EPA Method 533, Method 537.1, and expanding non-targeted approaches—is essential for evaluating what “PFAS removal” claims actually measure and what they might miss.
EPA Method 537.1: The Standard for Regulated Compounds
EPA Method 537.1 uses solid phase extraction followed by HPLC-MS/MS analysis to quantify 18 specific PFAS compounds in drinking water. This method was developed to support UCMR 3 monitoring and covers the primary regulated PFAS including PFOA, PFOS, PFNA, PFHxS, and HFPO-DA. Detection limits range from 1 to 20 ng/L depending on compound—adequate for current MCL compliance monitoring.
EPA Method 533: Expanding Short-Chain Coverage
EPA Method 533, finalized in 2019, covers 40 PFAS including short-chain compounds like PFBS and PFHxA not covered in Method 537.1. Method 533 achieves detection limits of 0.53–7.8 ng/L for its target compounds, providing much better analytical coverage of the short-chain PFAS that GAC cannot effectively remove. Utilities monitoring only with Method 537.1 lack analytical visibility into the short-chain compounds most likely to breach their carbon systems.
Non-Targeted Analysis: Seeing What We Do Not Know to Look For
Non-targeted analysis using high-resolution mass spectrometry (HRMS) can detect hundreds of PFAS compounds simultaneously without requiring compound-specific reference standards. This approach reveals the full PFAS complexity in source and treated water, often finding dozens of unregulated compounds not covered by targeted methods. Non-targeted analysis is research-grade today but is advancing toward standardization for compliance applications