Expanding Coverage for the Analysis of PFAS in Paper-Based Food Packaging Materials

Importance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are routinely applied to paper-based food contact materials (FCMs) for their oil- and water-repellent properties. Their extreme persistence and potential toxicity have raised concerns about migration into food and subsequent human exposure. Reliable screening and quantification of PFAS in packaging are essential to assess consumer risks and to guide regulatory policies.

Objectives and Study Overview

This study evaluated the occurrence of PFAS across 40 paper-based FCMs—including to-go boxes, popcorn bags and wrappers—using both targeted and nontargeted workflows. The goals were to develop a robust analytical protocol employing liquid chromatography–quadrupole time-of-flight mass spectrometry (LC/Q-TOF) and FluoroMatch software for comprehensive PFAS annotation, and to quantify those compounds relative to regulatory limits.

Methodology

Sample Preparation and Extraction:

• Forty FCM samples collected from restaurants and retailers in Montreal (2022–2023).
• Each sample (0.2 g) extracted with methanol (EPA 1633 diluent) via vortexing, sonication and repeated agitation (five cycles).
• Centrifugation (4,500 rpm, 10 min) and filtration (0.22 µm) yielded extracts stored at –20 °C.

Data Processing and Validation:

• Peak picking and alignment performed with Agilent Profinder; blank subtraction applied.
• FluoroMatch Modular and IonDecon workflows applied for homologous series detection, mass defect screening, accurate mass matching, in silico MS/MS matching, and confidence scoring.
• Method performance assessed via matrix-matched calibration (0.1–10 ng/mL), MDLs and MQLs based on procedural blanks (3σ, 10σ), precision (RSD ≤ 5%) and recoveries (82–94%).

Instrumentation Used

• Agilent 1290 Infinity II LC coupled to Agilent 6545 LC/Q-TOF.
• ZORBAX RRHD StableBond SB-C18 column (2.1 × 100 mm, 1.8 µm) with PFC-free conversion kit and delay column.
• Mobile phases: water + 20 mM ammonium acetate (A) and methanol (B); gradient elution at 0.4 mL/min; 50 °C column temperature; 10 µL injection.
• MS settings: drying gas 4 L/min (230 °C), sheath gas 12 L/min (375 °C), nebulizer 20 psi; All Ions fragmentation complemented by DDA-formatted .ms2 deconvolution.
• FluoroMatch software suite for suspect and nontarget PFAS screening; Agilent MassHunter Qualitative Analysis for file conversion.

Main Results and Discussion

The method exhibited excellent linearity (R² ≥ 0.99), low MDLs (0.003–0.61 ng/g) and high recoveries. Nontargeted analysis expanded PFAS coverage beyond the 18 standards used. Key findings:

• PFAS detected in all clamshell to-go boxes (max 356.6 ng/g), with PFOA (up to 187.2 ng/g) and PFDA (up to 92.2 ng/g) exceeding EU limit (25 μg/kg).
• Snack wrappers contained up to 75.2 ng/g PFAS (PFHxA most prevalent).
• Microwave popcorn bags showed lower levels (≤ 9.4 ng/g).
• No PFAS found in takeaway trays, paper straws or baking liners.

The hybrid suspect/nontarget approach improved annotation confidence, revealing additional perfluoroalkyl carboxylic and sulfonic acids not captured by targeted screening alone. Interactive mass defect and retention time plots facilitated series confirmation and outlier detection.

Benefits and Practical Applications

By coupling LC/Q-TOF with automated FluoroMatch workflows, laboratories can:

• Rapidly screen a broad PFAS library (> 15,000 species) without individual standards.
• Streamline data annotation, reduce manual review and improve reproducibility.
• Support regulatory compliance monitoring of FCMs and guide safer packaging design.

Future Trends and Potential Applications

Continued evolution in PFAS analysis may include:

• Expansion of spectral libraries and in silico fragmentation databases for emerging PFAS.
• Integration of ion mobility spectrometry for enhanced isomer separation.
• Application of non-target workflows to complex matrices (e.g., soils, biota).
• Real-time monitoring with ambient ionization techniques for rapid field screening.
• Development of stricter regulations driving innovation in PFAS-free materials.

Conclusion

The combined LC/Q-TOF and FluoroMatch approach delivers a robust, high-coverage workflow for PFAS detection in paper-based food packaging. The findings underscore widespread PFAS presence—particularly in clamshell to-go boxes—and highlight the need for tighter controls to minimize consumer exposure.

References

1. European Union. Regulation (EU) 2023/915 on PFAS limits in FCMs.
2. U.S. EPA. Our Current Understanding of the Human Health and Environmental Risks of PFAS.
3. Koelmel J. et al. Analytical Chemistry 2020, 92(16), 11186–11194.
4. Koelmel J. et al. Agilent Technol. App. Note 5994-7023EN, 2024.
5. Koelmel J. et al. J. Am. Soc. Mass Spectrom. 2023, 34, 2525–2537.