Determination of 30 Per- and Polyfluoroalkyl Substances in Dry Soybeans

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that can accumulate in food crops such as dry soybeans. Reliable, sensitive methods for simultaneous determination of multiple PFAS at trace levels are essential to support food safety monitoring, regulatory compliance, and risk assessment.

Objectives and Study Overview

This study aimed to develop and validate a complete analytical workflow for simultaneous determination of 30 individual PFAS in dry soybean powder. The procedure integrates QuEChERS extraction, enhanced matrix removal (EMR) mixed-mode passthrough cleanup, and quantification by triple quadrupole liquid chromatography–tandem mass spectrometry (LC/MS/MS), meeting AOAC SMPR 2023.003 performance criteria.

Methodology and Instrumentation

Sample extraction employed a buffered QuEChERS EN salt mixture and acetonitrile with 1% acetic acid. Cleanup used an Agilent Captiva EMR PFAS Food II cartridge under gravity and low-pressure conditions. Final extracts were reconstituted in 80:20 methanol/water.

Used Instrumentation

• Agilent 1290 Infinity II LC with PFC-free HPLC conversion kit and InfinityLab PFC delay column
• Agilent 6495D triple quadrupole LC/MS with Jet Stream iFunnel ESI source
• ZORBAX RRHD Eclipse Plus C18 analytical column and UHPLC guard
• Agilent MassHunter Workstation software for data acquisition and processing

Results and Discussion

EMR mixed-mode passthrough cleanup significantly improved PFAS recovery and matrix cleanliness compared to traditional dispersive SPE. Calculated LOQs ranged from 0.001 to 2.19 µg/kg; validated LOQs for core PFAS (PFOS, PFOA, PFNA, PFHxS) were ≤ 0.05 µg/kg, and ≤ 0.5 µg/kg for others, meeting AOAC SMPR requirements. Method recoveries fell within 65–135% (40–140% for PFAS without matching ISTD), with RSD ≤ 25% (≤ 30% without ISTD), across low, mid, and high QC levels.

Contributions and Practical Applications

The validated workflow provides a rapid, cost-effective, and robust solution for high-throughput PFAS screening in soybean matrices. It supports food safety laboratories, regulatory agencies, and research facilities by delivering reliable data for risk assessments and compliance.

Future Trends and Opportunities

• Extension of the EMR passthrough approach to other complex food matrices (grains, dairy, meat).
• Automation of sample preparation for higher throughput and reduced variability.
• Integration with high-resolution mass spectrometry for untargeted PFAS screening and novel contaminant discovery.
• Application of machine learning for data analysis and trend prediction in PFAS contamination.

Conclusion

The combined QuEChERS-EMR cleanup and LC/TQ method meets stringent validation criteria for PFAS analysis in dry soybeans. It offers improved sensitivity, accuracy, and throughput, making it well suited for routine monitoring and regulatory compliance.

References

1. AOAC. Standard Method Performance Requirements (SMPR 2023.003) for PFAS in food and feed matrices. 2023.
2. Zhao L., Giardina M., Parry E. Determination of 30 PFAS in infant formula, milk, and eggs using Captiva EMR PFAS Food II cleanup and LC/MS/MS. Agilent Technologies Application Note 5994-7366EN, 2024.