Repeatability and Reproducibility of the Oasis™ GCB/WAX for PFAS Analysis Cartridges in Soil/Solid Samples for EPA Method 1633

Importance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants of growing regulatory concern. EPA Method 1633 extends PFAS monitoring beyond drinking water to diverse matrices including soil, biosolids, and tissues. Reliable sample preparation workflows for these complex media are essential to ensure accurate, reproducible quantitation for environmental risk assessment and compliance.

Objectives and Study Overview

This study evaluates the repeatability and reproducibility of the Oasis GCB/WAX dual-phase solid-phase extraction cartridge for PFAS analysis in soil samples following EPA Method 1633. Three production lots of cartridges were tested with six replicate soil extractions each to assess performance consistency against method acceptance criteria for analyte recovery and precision.

Methodology and Instrumentation

• Sample Preparation: Soil samples were extracted and cleaned using the Oasis GCB/WAX cartridge, integrating graphitized carbon black and weak anion exchange phases into a single device. This approach streamlines cleanup and reduces manual steps by up to 20% compared to separate sorbents.
• LC-MS/MS Analysis: Separation was achieved on an ACQUITY UPLC I-Class Plus FTN system with a Premier BEH C18 analytical column and an Atlantis Premier BEH C18 AX isolator column, using a gradient of 2 mM ammonium acetate in water and acetonitrile. Detection employed a Xevo TQ-XS triple quadrupole mass spectrometer operating in negative electrospray ionization mode.

Used Instrumentation

• Oasis GCB/WAX dual-phase SPE cartridge
• ACQUITY UPLC I-Class Plus FTN system
• Premier BEH C18 and Atlantis Premier BEH C18 AX columns
• Xevo TQ-XS triple quadrupole MS
• MassLynx software

Key Results and Discussion

The Oasis GCB/WAX cartridges consistently met EPA 1633 acceptance criteria across all three lots, with mean recoveries generally within 70–130% and relative standard deviations below specified thresholds. Most PFAS compounds showed minimal inter-batch variability, demonstrating that no protocol optimization was required to achieve method compliance. A few analytes lacking formal EPA criteria also exhibited acceptable precision, further supporting cartridge robustness.

Benefits and Practical Applications

• Streamlined workflow: Combined cleanup and extraction simplifies sample preparation and reduces hands-on time.
• Reproducibility: Consistent performance across production lots ensures reliable PFAS quantitation in soil and other solid matrices.
• Regulatory compliance: Meets stringent EPA Method 1633 criteria for recovery and precision, supporting environmental monitoring and quality control.

Future Trends and Opportunities

Advancements may include expanded sorbent chemistries to target emerging PFAS, integration into automated platforms for high-throughput analysis, and coupling with high-resolution mass spectrometry for broader screening. Field-deployable SPE devices could also facilitate on-site PFAS monitoring in environmental matrices.

Conclusion

The dual-phase Oasis GCB/WAX cartridge delivers reproducible, out-of-the-box performance for PFAS extraction from soil as defined by EPA Method 1633. Its combined sorbent design and validated QC release process provide a robust, efficient solution for analysis of complex solid matrices in environmental laboratories.

References

1. US Environmental Protection Agency. Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Soil, Solid, Biosolids, and Tissue Samples by LC-MS/MS; Final Version, January 31, 2024.
2. Organtini K, Rosnack K, Plummer C, Hancock P, Burt O. Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Accordance With EPA 1633 Part 2: Analysis of Soil Matrices; Waters Application Note 720008143, 2023.
3. Organtini K, Rosnack K, Plummer C, Hancock P, Burt O. Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Accordance With EPA 1633 Part 3: Analysis of Soil and Tissue; Waters Application Note 720008230, 2024.