Determination of PFOS and PFOA in Food Matrix of Animal Origin Using UHPLC Hyphenated Triple Quadrupole Tandem Mass Spectrometry

Significance of the Topic

Perfluoroalkyl substances (PFAS) such as PFOA and PFOS are persistent organic pollutants with high stability and bioaccumulation potential. Their presence in animal-derived foodstuffs poses health risks including developmental, immunological and hormonal effects. Monitoring trace levels of PFAS in food matrices is therefore essential to ensure compliance with tolerable daily intake limits and protect public health.

Study Objectives and Overview

This work aimed to develop and validate an ultrasensitive and selective UHPLC-MS/MS method for simultaneous quantification of PFOA and PFOS in fish, shrimp and egg matrices. The method was benchmarked by single-lab spiking tests, inter-laboratory validation and application to real sample surveys.

Methodology and Instrumentation

Sample Preparation:

• 5 g homogenized matrix spiked with stable isotope internal standards (13C8-PFOA, 13C4-PFOS).
• Triple extraction with methanol followed by weak anion exchange (WAX) cleanup.
• Evaporation and reconstitution in methanol for analysis.

UHPLC-MS/MS Conditions:

• Instrument: Agilent 1290 Infinity UHPLC coupled to 6460 Triple Quadrupole with JetStream ESI in negative mode.
• Column: C18, 100×2.1 mm, 1.8 µm, 30 °C, 0.2 mL/min gradient elution.
• MRM transitions optimized: PFOA (412.9→368.9), PFOS (498.9→130.0) and confirmatory ions.

Main Results and Discussion

Calibration and Sensitivity:

• Linear dynamic range: 0.01–10 µg/L for PFOA; 0.1–40 µg/L for PFOS (R2≥0.999).
• Limits of detection: 0.002 µg/kg (PFOA), 0.02 µg/kg (PFOS); LOQ: 0.01 µg/kg and 0.1 µg/kg respectively.

Accuracy and Precision:

• Spiking recoveries in fish, shrimp and egg at LOQ, 5× and 10× LOQ ranged 79–113% with RSD 3–11% (n=6).
• Inter-laboratory validation across five labs yielded recoveries 87–106% and RSD 11–31%.

Real Sample Survey:
Analysis of 150 commercial samples showed a 15% positive rate for PFOS (0.04–3.0 µg/kg), highest in fish.

Benefits and Practical Applications

The method combines high sensitivity, wide dynamic range and reliable selectivity, suitable for routine food safety monitoring laboratories conducting QA/QC and regulatory compliance testing for PFAS residues in animal-origin foods.

Future Trends and Opportunities

Technological advances such as high-resolution MS and miniaturized sample preparation could further lower detection limits and throughput times. Expanding scope to other emerging PFASs and integrating automated workflows will enhance surveillance of a broader pollutant spectrum in complex food matrices.

Conclusion

An Agilent UHPLC-MS/MS method with WAX cleanup was established for robust quantitation of PFOA and PFOS in animal-based foods, demonstrating low ng/kg sensitivity, high accuracy and inter-laboratory reproducibility. The approach is ready for implementation in routine monitoring to safeguard food quality and public health.

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