EPA Method 1633 Application Note Summary

This application note describes the use of EPA Method 1633, a draft protocol designed to analyze 40 per- and polyfluoroalkyl substances (PFAS) in aqueous samples using solid-phase extraction (SPE) and LC-MS/MS. Developed in response to increasing concern over PFAS contamination, this method incorporates isotope dilution and includes 24 extracted and 7 non-extracted isotopically labeled internal standards for accurate quantification. UCT’s Enviro-Clean® WAX SPE cartridges and SelectraCore® C18 HPLC columns are employed to ensure effective separation and recovery, including resolution of branched vs. linear isomers of PFHxS and PFOS. A C18 delay column is used to mitigate background contamination from the HPLC system. Analytical results showed excellent linearity (R² > 0.99), recoveries between 80–110%, and relative standard deviations (RSD) below 10% at both low and high spiking levels. This method aligns with the EPA’s Unregulated Contaminant Monitoring Rule 5 (UCMR5) and expands upon previous PFAS testing methods (EPA 537.1 and 533). Sample preparation includes conditioning, extraction, drying, and elution steps, followed by carbon cleanup and filtration before LC-MS/MS analysis. The method is specifically engineered to reduce PFAS contamination risks during analysis, recommending the use of PEEK tubing and providing precise parameters for reproducibility and system optimization.