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

Significance of the Topic

Perfluoroalkyl and polyfluoroalkyl substances PFAS are industrial chemicals with exceptional stability and widespread environmental persistence. Their presence in dairy products raises concerns due to potential adverse health effects, bioaccumulation in the food chain, and strict regulatory limits. Reliable measurement of PFAS at trace levels in high-fat matrices such as milk is essential for risk assessment, food safety, and compliance with international standards.

Objectives and Study Overview

The primary goal was to develop and validate a rapid, single-laboratory method for quantifying 30 PFAS in whole milk. Specific aims included optimizing extraction from a high-fat matrix, achieving baseline chromatographic separation of target analytes and interferences in under ten minutes, and meeting the performance criteria defined by AOAC SMPR 2023.003.

Methodology and Used Instrumentation

The method combined QuEChERS extraction with isotope dilution quantitation. Ten-gram milk samples were spiked with native PFAS standards and 16 isotopically labeled internal standards at 0.01, 0.1, and 1.0 ng/g. After acidification and acetonitrile addition, samples underwent dispersive SPE cleanup. Chromatographic separation was performed on a Shimadzu Nexera UHPLC system coupled to an LCMS-8060NX triple quadrupole mass spectrometer. Over 1980 instrument parameter combinations and six column/gradient setups were evaluated to maximize peak shape, resolution, and signal-to-noise performance.

Main Results and Discussion

Calibration was linear across the 0.05 to 10 ng range with residuals within ±25%. All 30 PFAS were separated within nine minutes, including baseline resolution of branched and linear isomers and separation from cholic acid interferences. Limits of quantitation met or exceeded AOAC SMPR requirements. Recoveries ranged from 88% to 118% with relative standard deviations below 12%, demonstrating robust precision and accuracy in a challenging matrix.

Benefits and Practical Applications

• High throughput analysis suitable for routine food safety laboratories
• Comprehensive coverage of long-chain and short-chain PFAS
• Reliable quantitation in fatty matrices using isotope dilution
• Compliance with international method performance standards

Future Trends and Potential Applications

Ongoing developments may include expansion to additional food matrices, integration of high-resolution mass spectrometry for non-target screening, and coupling with automated sample preparation to further increase throughput. Emerging regulations will drive demand for even lower detection limits and broader PFAS panels.

Conclusion

This single-laboratory validation demonstrates that QuEChERS extraction combined with Shimadzu UHPLC-MS/MS provides a rapid, sensitive, and accurate approach for quantifying 30 PFAS in whole milk. The method fulfills stringent AOAC SMPR 2023.003 criteria and is readily applicable to routine monitoring of dairy products for food safety assurance.

Reference

No external literature references were provided in the original document.