Determination of Per- and Polyfluoroalkyl Substances in Soil and Sediment

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants found widely in soil and sediment. Accurate quantitation of 40 PFAS compounds in solid matrices is critical for environmental monitoring, risk assessment and regulatory compliance. The standardized EPA Method 1633 ensures data comparability across laboratories.

Objectives and Study Overview

This study evaluated a modified sample preparation protocol using blended dual-phase solid-phase extraction (SPE) cartridges containing Agilent Bond Elut PFAS WAX and Carbon S sorbents. The goals were to simplify the extraction workflow, adhere to EPA 1633 performance criteria and demonstrate reliable PFAS recovery in soil and sediment samples.

Methodology

Sample extraction followed the solid matrix procedure of EPA 1633 with minor adaptations for blended sorbents.

• Five grams of dried soil or sediment were spiked with isotopically labeled internal standards and equilibrated.
• Sequential extraction steps employed 0.3% ammonium hydroxide in methanol.
• Extracts were concentrated under nitrogen and adjusted to pH 6.5 before SPE cleanup.
• SPE cartridges were conditioned with formic acid and eluted with ammonium hydroxide in methanol.
• Final eluates were neutralized, filtered, and analyzed by LC-MS/MS.

Instrumentation

The analytical platform comprised an Agilent Infinity II LC system modified with PFAS-free components coupled to an Agilent 6475A triple quadrupole mass spectrometer with Jet Stream electrospray ionization. Chromatographic separation used a ZORBAX RRHD Eclipse Plus C18 column and a gradient of ammonium acetate aqueous phase and acetonitrile.

Main Results and Discussion

Cartridge blank tests confirmed negligible PFAS background, with all residues below half the limit of quantitation (LOQ). Duplicate analyses of topsoil and river sediment showed reproducible concentrations for most PFAS (RPD < 30%), with a few near-LOQ compounds exhibiting higher variability. Matrix spike recoveries and duplicates met the ongoing precision and recovery limits defined by EPA 1633, demonstrating method robustness. Isotopically labeled internal standard recoveries for all samples fell within acceptance criteria, confirming analytical integrity.

Benefits and Practical Applications

The blended dual-phase SPE approach integrates extraction and matrix reduction in one step, reducing hands-on time and consumable use. It maintains high recovery, reproducibility and compliance with regulatory standards. This streamlined workflow is well suited for routine environmental monitoring laboratories performing PFAS analysis in soils and sediments.

Future Trends and Potential Applications

Advancements may include automated SPE systems for high-throughput testing, miniaturized cartridges for lower sample volumes, and expanded sorbent chemistries to target emerging PFAS compounds. Integration with field-deployable sample preparation devices and real-time monitoring tools could further enhance environmental surveillance.

Conclusion

Blended Agilent Bond Elut PFAS WAX/Carbon S SPE cartridges provide an effective, simplified alternative to layered sorbent configurations for the extraction of 40 PFAS from soil and sediment. The method meets all EPA Method 1633 criteria, offering reliable performance and streamlined workflows for environmental laboratories.

References

1. U.S. Environmental Protection Agency. Method 1633A: Analysis of Per- and Polyfluoroalkyl Substances in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS. EPA 820-R-24-007, December 2024.
2. Novello A., Mihelich B., Giardina M. Automated Solid Phase Extraction of PFAS from Aqueous Samples Using Dual-Phase Agilent Bond Elut PFAS WAX/Carbon S SPE Cartridges for US EPA Method 1633. Agilent Technologies Application Note 5994-8289EN, 2025.
3. U.S. Department of Defense. Data Validation Guidelines Module 6: Data Validation Procedure for PFAS Analysis by QSM Table B-24. October 2022.