Determination of 30 PFAS in Seafood by Liquid Chromatography Triple Quadrupole Mass Spectrometry (LC-MS/MS)

Significance of the Topic

Per- and polyfluorinated substances (PFAS) are persistent environmental contaminants linked to adverse health effects. Monitoring their levels in seafood is critical for food safety, regulatory compliance, and public health protection. The ability to accurately quantify trace PFAS in complex matrices such as shrimp supports risk assessment and informs industry practices.

Study Objectives and Overview

This study presents a single-laboratory validation for the determination of 30 PFAS compounds in shrimp using a rapid QuEChERS extraction and UHPLC coupled to a triple quadrupole mass spectrometer. The method was benchmarked against AOAC SMPR 2023.003 criteria for accuracy, precision, and limit of quantitation (LOQ).

Methodology and Instrumentation

The approach combines:

• QuEChERS extraction: shrimp samples spiked with native PFAS and isotopically labeled standards, vortexed with acetonitrile and QuEChERS salts, centrifuged, and supernatant cleaned via WAX SPE.
• Concentration step: final extract reduced to 400 µL in methanol-water for enhanced sensitivity.
• UHPLC separation: Shimadzu Nexera system, nine-minute gradient, optimized for baseline resolution of branched/linear isomers and separation from endogenous cholic acids.
• Mass spectrometry: Shimadzu LCMS-8060NX with heated electrospray ionization in negative mode, using multiple reaction monitoring (MRM) transitions and isotope dilution quantitation.

Main Results and Discussion

Calibration and validation data show:

• Linear matrix-matched calibration from 0.001 to 10 ng/g with accuracy within 92–116% for target analytes (PFOA, PFHxS, PFNA, PFOS examples).
• LOQs between 0.0055 and 0.55 ng/g for all 30 PFAS, meeting or exceeding AOAC SMPR 2023.003 requirements.
• Recoveries ranged from 76% to 123% across spike levels of 0.0055, 0.055, 0.55, and 5.5 ng/g, with relative standard deviations below 21%.
• Excellent chromatographic performance: nine-minute runtime, clear peak shapes, and baseline separation of isomeric forms and interfering bile acids.

Benefits and Practical Applications

This validated method offers:

• High throughput analysis suitable for routine monitoring laboratories.
• Robust quantitation down to sub-ng/g concentrations in seafood matrices.
• Compliance with international validation standards for regulatory testing.

Future Trends and Potential Uses

Advancements may include:

• Expansion to additional food matrices and environmental samples.
• Integration of high-resolution MS to further resolve isomeric PFAS species.
• Automation of extraction and cleanup workflows for higher sample throughput.

Conclusion

The combination of QuEChERS extraction, rapid UHPLC separation, and sensitive triple quadrupole detection provides a robust, precise, and accurate protocol for the quantitation of 30 PFAS in shrimp. Results satisfy AOAC SMPR 2023.003 criteria, supporting its adoption for routine seafood safety testing.

Reference

AOAC SMPR 2023.003