Simultaneous Quantitation of 32 PFAS in Baby Food by LC-MS/MS

Importance of the topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants known as "forever chemicals" due to their resistance to degradation. They accumulate in food chains and pose health risks, especially in sensitive populations such as infants. Reliable quantification of PFAS in baby food is essential for ensuring consumer safety and regulatory compliance.

Study objectives and overview

This work presents a single-laboratory validation of a rapid LC-MS/MS method for simultaneous determination of 32 PFAS compounds in infant formula. The protocol employs a streamlined QuEChERS extraction with dispersive solid-phase cleanup and operates without isotopically labeled internal standards, yet meets the acceptance criteria of AOAC SMPR 2023.003.

Methodology and instrumentation

A sample of 5.0 g infant formula is mixed with water and acetonitrile, followed by MgSO4 and sodium acetate addition for phase separation. After centrifugation, a dSPE sorbent cleans the extract. The aliquot is evaporated to dryness under nitrogen and reconstituted in methanol:water (80:20, v/v). Calibration standards (0.005–10 μg/L, up to 0.25–10 μg/L for PFBA) are prepared externally, and fortified samples at 0.01, 0.05, and 0.25 μg/kg are analyzed in six replicates. Chromatographic separation is achieved within 20 minutes using multiple reaction monitoring (MRM) with optimized MS parameters.

Used instrumentation

• Shimadzu LCMS-8060NX triple quadrupole mass spectrometer
• Shimadzu Nexera X3 UHPLC system
• Dr. Ehrenstorfer EPA Method 533 PFAS Mixture reference standards

Main results and discussion

Method specificity was confirmed by blank injections showing <30% response of the reporting limit. System precision yielded retention time RSD <0.1 min and peak area RSD <20%. Linearity of matrix-matched calibration curves produced R² values above 0.967. Limits of quantitation met AOAC SMPR criteria for all analytes. Mean recoveries ranged from 65% to 135%, with repeatability (RSDr) <25% and within-lab reproducibility (RSDR) <40% at the LOQ levels.

Benefits and practical applications

• Simple QuEChERS workflow without isotopic standards
• Short 20 min run time enables high throughput
• Meets stringent AOAC SMPR acceptance criteria
• Applicable for routine quality control in food testing laboratories

Future trends and possibilities of application

• Extension to other food and environmental matrices
• Automation of sample preparation to enhance consistency
• Integration of high-resolution MS for non-targeted PFAS screening
• Adaptation to evolving regulatory limits and new PFAS analogs

Conclusion

The developed LC-MS/MS method offers a fast, robust, and sensitive solution for multi-PFAS analysis in infant formula. With straightforward sample preparation, compliance with regulatory guidelines, and high throughput, this approach supports reliable PFAS monitoring in food safety laboratories.