Development of a Standard PFAS Method for the Evaluation of PFAS in Food Contact Materials

Significance of the topic

Per- and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative chemicals widely used for water-, oil-, and heat-resistant properties in consumer products, including food contact materials. Growing regulatory restrictions and public-health concerns drive demand for reliable analytical methods to detect and quantify PFAS in packaging. Standardized, reproducible assays are needed to support regulatory compliance, consumer safety assessments, and inter-laboratory comparability.

Objectives and study overview

This study presents development and validation of a targeted LC-MS/MS method to screen and quantify 45 PFAS and 25 isotopically labeled surrogate compounds in diverse food packaging matrices. The method was developed jointly by RJ Lee Group and Shimadzu Scientific Instruments, following ASTM guidelines, and aims to provide a fast, cost-efficient workflow that avoids solid-phase extraction (SPE) while maintaining sensitivity and reproducibility across multiple matrix types.

Methodology

• Sample selection: Seventeen representative food-contact materials were purchased to cover hard plastics, soft plastics, paper products, and aluminum foil (examples: lettuce clamshell, TetraPak milk, microwavable rice bags, coffee pods, baking cup liners, coffee filters, aluminum foil).
• Sample preparation (representative workflow):
  • Weigh 0.5 g sample into a cleaned 50 mL centrifuge tube (cutting tools rinsed with acetonitrile and methanol between cuts to avoid contamination).
  • Spike with isotopic surrogate solution and equilibrate ~15 min.
  • Add 10 mL of 50:50 methanol:water, vortex; adjust to pH 9–10 with ammonium hydroxide and tumble for 2 hours for cosolvent extraction.
  • Centrifuge 3,000 rpm for 15 min at 8 °C, adjust extract to pH 3–4 with acetic acid, vortex.
  • Filter through preconditioned 0.2 µm polypropylene syringe filter into a centrifuge tube and transfer aliquots to silanized glass vials with PTFE/ silicone septa.
• Calibration: Stock native and labeled standards diluted in 95:5 methanol:water. An 8- or 9-point calibration curve prepared in 50:50 methanol:water with 0.1% acetic acid; reporting ranges depended on analyte and spanned approximately 100–20,000 ng/kg in matrix. Acceptance criteria included R2 > 0.99, RSE < 30% and RF RSD < 30%.

Instrumentation used

• Liquid chromatography: Shimadzu Nexera UHPLC system with Shimadzu Nexcol PFAS Delay (50 x 3.0 mm, 5 µm) as a delay column and Shim-pack Scepter C18-120 analytical column (2.1 x 100 mm, 3 µm). Mobile phases: A = 2 mmol/L ammonium acetate in H2O/ACN (95/5), B = acetonitrile. Flow rate 0.45 mL/min, column oven 45 °C. Gradient programmed to elute all targets within ~11.5 min; co-injection function used to improve early-eluting peak shape. Autosampler rinsing solvent: 60/40 acetonitrile/2-propanol.
• Mass spectrometry: Shimadzu LCMS-8060NX triple-quadrupole MS/MS. Key source parameters: interface temperature 170 °C, probe position +3 mm, nebulizer gas 3 L/min, heating gas 15 L/min, interface voltage -0.5 kV, DL 200 °C, heatblock 300 °C, drying gas 8 L/min.

Main results and discussion

• Chromatography: Adequate peak shapes were achieved for all analytes; co-injection improved early-eluting compounds. Complete elution of target PFAS occurred within ~11.5 minutes, enabling high throughput.
• Quantitation and calibration: Linear calibration curves were obtained for all native and surrogate compounds with R2 > 0.99 and acceptable residual/precision metrics as defined. Reporting ranges varied by analyte (typical reporting range 100–20,000 ng/kg depending on compound).
• Recovery and precision: Surrogate spike recoveries were evaluated across matrices; representative surrogate spike (1600 ng/kg on 0.5 g) showed generally acceptable recovery and %RSD values. Example matrices (soft plastics and foil) demonstrated consistent recoveries and repeatability (figures summarized qualitatively rather than transcribed).
• Method simplification: The optimized cosolvent extraction procedure eliminated the need for SPE cleanup while maintaining sensitivity, reducing both labor and consumable costs.
• Practical considerations: Strict cleaning of cutting tools and use of silanized vials were emphasized to minimize contamination. Matrix-dependent effects were observed, so matrix-matched calibration or surrogate correction remain important for accurate quantitation.

Benefits and practical applications

• High throughput screening of PFAS in a wide range of food packaging materials with run times under 12 minutes per injection.
• Cost and time savings by removing SPE from the workflow while preserving analytical performance for the 45 targeted PFAS.
• Applicable for regulatory monitoring, product screening, supplier verification, and research studies assessing consumer exposure from packaging.

Future trends and applications

• Standardization and inter-laboratory validation: Wider adoption will require ring trials and harmonized protocols to ensure reproducibility across labs and instruments.
• Extension to non-target and suspect screening: Complementing targeted assays with high-resolution mass spectrometry could capture novel or replacement PFAS species not covered by the 45-target list.
• Lower detection limits and miniaturized workflows: Further optimization could push reporting limits lower and reduce sample mass required, important for trace-level regulatory limits.
• Matrix-specific method refinements: Tailored extraction or cleanup could improve accuracy for challenging matrices (e.g., fatty films, heavily coated papers) where matrix effects are pronounced.

Conclusion

A robust LC-MS/MS method for 45 PFAS plus 25 isotopically labeled surrogates in diverse food-contact materials was developed using Shimadzu LCMS-8060NX instrumentation. The validated procedure employs a cosolvent extraction that avoids SPE, achieves linear calibration and acceptable precision across matrices, and delivers rapid chromatographic turnaround. The method supports efficient screening and quantitation of PFAS in packaging, though further inter-laboratory validation and continued attention to matrix effects are recommended for routine regulatory implementation.

References

• ASTM D8421-21