Analysis of Per-and Polyfluoroalkyl Substances (PFASs) in Soil and Tissue Using Weak-Anion Exchange SPE and LC-MS/MS Analysis According to EPA Method 1633

Polyfluoroalkyl Substances (PFAS) in the Environment
Poster Presentation

Prepared by A. Abdelkaoui
United Chemical Technologies Inc, 2731 Bartram Rd, Bristol, PA, 19007, United States

Contact Information: [email protected]; 215-781-9255


Per-and polyfluoroalkyl substances (PFASs) are a diverse group of synthetic organofluorine compounds that are widely used in industrial applications and consumer products. PFASs are persistent in the environment, are resistant to degradation, and are known to bioaccumulate in humans and wildlife. PFASs have historically been analyzed in drinking water according to EPA 537 (14 compounds) and 537.1 (18 compounds). An updated method, EPA 533, has been validated for the analysis of multiple short-chain PFAS’s, including telomers and precursor compounds, that cannot be measured by EPA 537.1. EPA 533 measures PFAS’s by isotope dilution anion-exchange solid-phase extraction (SPE) and liquid chromatography/tandem mass spectrometry (LC-MS/MS). In August 2021, the EPA released the first draft for EPA 1633 method that allows for analyzing 40 target PFAS analytes in a single extraction. As of December 2022, the EPA released a third draft method addressing some of the issues in the earlier versions. Throughout the development process, we noticed an increased difficulty in extracting these analytes from complex matrices as in soil and tissue. Furthermore, it includes the use of 24 isotopically labeled Isotope Dilution Standards and 7 Isotope Performance Standards to ensure optimum method performance. In light of the EPA’s recent announcement on the fifth Unregulated Contaminant Monitoring Rule (UCMR5), which includes 29 PFAS’s, the use of EPA 1633 is set to become increasingly important to testing labs.
This Poster outlines the analysis of PFAS’s in soil and fish tissue according to EPA 1633 draft method utilizing UCT’s Enviro-Clean® polymeric weak-anion exchange (WAX) SPE cartridges. LC-MS/MS analysis was carried out using a SelectraCore® C18 HPLC analytical column, while a short (5cm) C18 delay column was used to reduce potential PFAS contamination from the HPLC system. The chromatography was optimized to obtain maximum resolution with minimum co-elution of isomers, including the critical linear and branched isomers of PFHxS and PFOS. For quantitation, a six-point calibration (According to Table 4) was performed, and all compounds were found to be linear with R2 values > 0.99. The extraction method was evaluated by spiking reagent water samples with PFAS’s at a low and high fortification levels. Recoveries of all analytes were within a range of 85-110% and RSD values <10%.