Analysis of PFAS in Breast Milk: An Alternative Sample Prep

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants, with thousands of variants used in industry and consumer products over decades.
Their stability and potential health impacts drive increasing monitoring efforts in biological matrices like breast milk, critical for assessing infant exposure and guiding regulatory standards.

Objectives and Study Overview

This study compares a conventional weak anion exchange (WAX) solid phase extraction method, based on EPA Method 1633, to a streamlined approach using Captiva EMR-Lipid cartridges for PFAS analysis in breast milk.
The aim is to evaluate workflow efficiency, background reduction, and analytical performance for both protocols.

Methodology and Instrumentation

• Sample Preparation
  
  • WAX SPE: Following draft EPA Method 1633, breast milk aliquots undergo conditioning, loading, washing, elution, and reconstitution steps.
  • EMR-Lipid Filtration: Two grams of milk are mixed with acetonitrile, sonicated, centrifuged, and filtered through Captiva EMR-Lipid cartridges, followed by a rinse step, drying, and reconstitution.
• Instrumentation
  
  • Agilent 1290 Infinity II LC system with binary pump, multisampler, column compartment.
  • Agilent 6470 Triple Quadrupole LC/MS with JetStream electrospray source.
  • Chromatographic conditions: Zorbax EclipsePlus C18 RRHD column (2.1×100 mm, 1.8 µm), gradient elution with ammonium acetate aqueous phase and acetonitrile, flow rate 0.4 mL/min, 40 °C column temperature.
  • MS conditions: MRM acquisition, optimized source parameters (gas temperatures, flows, voltages) to minimize PFAS background.

Main Results and Discussion

• Background Reduction: EMR-Lipid filtration selectively removes phospholipids, significantly lowering matrix background compared to WAX SPE, as evidenced by overlaid chromatograms.
• Recovery and Sensitivity: Both methods achieved comparable or improved recoveries for target PFAS compounds, with adequate sensitivity at 100 ppt levels.
• Workflow Efficiency: EMR-Lipid protocol reduces preparation steps and total processing time, minimizing the risk of contamination and sample loss.

Benefits and Practical Applications

• Rapid, simplified sample preparation without extensive SPE steps.
• Effective phospholipid removal enhances data quality.
• Cost and time savings for laboratories performing routine PFAS monitoring in breast milk.
• Facilitates compliance with regulatory guidelines by streamlining method implementation.

Future Trends and Opportunities

• Expansion of EMR-Lipid filtration to other complex biological matrices (e.g., serum, tissue).
• Integration with high-resolution mass spectrometry for broader PFAS screening.
• Automated sample prep workflows to increase throughput and reproducibility.
• Further method validation for additional PFAS classes and emerging compounds.

Conclusion

The Captiva EMR-Lipid filtration approach offers a viable alternative to traditional WAX SPE for PFAS analysis in breast milk, delivering efficient phospholipid removal, comparable analytical performance, and streamlined workflows suitable for high-volume testing.

References

• US EPA. Draft Method 1633: Analysis of Per- and Polyfluoroalkyl Substances in Environmental Samples by LC-MS/MS, December 2022.
• Zheng, G. et al. Per- and Polyfluoroalkyl Substances in Breast Milk: Concerning Trends for Current-Use PFAS. Environmental Science & Technology, 2021, 55, 7510–7520.