Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Solid Samples

Importance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that pose health and ecological risks. Robust analytical methods for extraction, cleanup, and quantitation of PFAS in solid matrices are essential for regulatory compliance and environmental monitoring. This study evaluates Agilent Bond Elut PFAS WAX SPE cartridges combined with Agilent Carbon S cleanup following US EPA draft method 1633.

Objectives and Study Overview

• Evaluate the recovery and precision of Agilent PFAS Bond Elut WAX SPE and Carbon S cleanup in solid samples.
• Compare performance metrics against the US EPA draft method 1633 single-lab validation data.
• Assess matrix effects using both reagent sand and real topsoil samples.

Methodology and Instrumentation

Sample Preparation and Extraction

• Reagent sand and topsoil samples spiked with native PFAS and isotopically labeled internal standards.
• SPE extraction using Agilent Bond Elut PFAS WAX cartridges, followed by Carbon S sorbent cleanup.
• Final extracts diluted to volume, filtered, and analyzed by LC–MS/MS.

Used Instrumentation

• Agilent 1290 Infinity II LC system modified with PFC-free conversion kit.
• Agilent 6470B triple quadrupole LC/MS with Jet Stream ESI source.
• Agilent MassHunter Workstation software and PFAS MRM database for optimized detection.

Main Results and Discussion

• Average native PFAS recovery in reagent sand: 98 ± 2%, compared to 94 ± 4% reported in the draft method.
• Overall precision (RSD): 3.8 ± 0.6%, matching the draft method’s 3.9 ± 0.6% and well below the 20% threshold.
• Method detection limits (MDLs): Comparable to or improved over draft method values for most PFAS congeners.
• Extracted internal standard recoveries in topsoil: 101 ± 4% (96 measurements).
• Non-extracted internal standard recoveries: 87–104%, within acceptable 50–150% range.
• Method blanks: PFAS background levels were negligible and below minimum quantitation limits.
• Topsoil matrix spike recoveries: 97 ± 1%, indicating minimal matrix effects and accurate quantitation.

Benefits and Practical Applications

• Validated workflow offers reliable PFAS quantitation in diverse solid matrices such as soils, sediments, and biosolids.
• High recoveries and precision support regulatory monitoring and quality assurance protocols.
• Method flexibility allows adaptation to varied environmental sample types.

Future Trends and Potential Applications

• Integration with high-resolution mass spectrometry for comprehensive PFAS screening.
• Automation of SPE and cleanup processes to improve laboratory throughput.
• Expansion to emerging PFAS classes and further harmonization of global testing standards.

Conclusion

The combination of Agilent Bond Elut PFAS WAX SPE cartridges and Carbon S cleanup delivers performance on par with or exceeding US EPA draft method 1633 for solid samples, offering precise recoveries, low detection limits, and robust matrix handling for environmental PFAS analysis.

Reference

1. US EPA Draft Method 1633: Analysis of PFAS in Aqueous and Solid Samples, December 2022.
2. Giardina M. Application Note 5994-4960EN, Agilent Technologies, 2022.
3. US EPA Method 533: PFAS in Drinking Water by LC-MS/MS, 2019.
4. US EPA Method 537.1: PFAS in Drinking Water by SPE and LC-MS/MS, 2018.
5. DoD/DOE Quality Systems Manual Version 5.4, 2021.