Comprehensive screening of per- and polyfluoroalkyl substances (PFAS) in food contact materials

Significance of the Topic

Per- and polyfluoroalkyl substances (PFAS) are widely used in food contact materials (FCM) to provide grease and water repellency but are persistent, bioaccumulative, and toxic. Their potential migration into food and release into the environment pose significant health and regulatory concerns, driving the need for comprehensive screening methods.

Objectives and Study Overview

This work aimed to develop a robust, automated combustion ion chromatography (CIC) method to quantify total organic fluorine (TOF) and extractable organic fluorine (EOF) in various FCM. A non-targeted high-resolution mass spectrometry (LC-HRMS) approach was also applied to characterize individual PFAS compounds in extracted fractions.

Methodology and Instrumentation

Combustion ion chromatography workflow:

• Sample preparation: Cryogenic milling (SPEX Freezer/Mill) to 30–50 µm powder; water extraction for total inorganic fluorine; accelerated solvent extraction (Thermo Scientific™ EXTREVA™ ASE™) with 80% methanol/20% acetonitrile; low-temperature evaporation (Genevac™ Rocket Synergy™ 2); solvent reconstitution.
• CIC analysis: Thermo Scientific™ Dionex™ Integrion™ HPIC™ system with Dionex EGC 500 KOH eluent generator, CR-ATC 600 trap column, ADRS 600 suppressor, and Nittoseiko™ AQF-2100H combustion-absorption unit; quantification of TF, TIF (direct injection mode), EF (combustion mode), and EIF (direct injection mode).
• Non-targeted LC-HRMS: Vanquish™ Flex UHPLC with Hypersil GOLD delay column and Orbitrap™ Exploris 240; heated electrospray ionization; top-4 data-dependent MS2; Compound Discoverer™ software workflows with mzCloud™, NIST, Getzinger in silico PFAS libraries, FluoroMatch fragment database, and user-defined PFAS mass lists.

Main Results and Discussion

Three of eight FCM samples showed TF levels from 1,083 to 2,142 µg/g, far exceeding regulatory limits (e.g., 100 µg/g). Inorganic fluorine (TIF, EIF) was negligible. EOF accounted for only 3–13% of TOF, indicating that targeted LC-MS screening of EOF would miss many fluorinated compounds. Non-targeted LC-HRMS identified 46 PFAS species in EOF fractions, with perfluorocarboxylic acids (C3–C8) being the dominant homologous series. Other detected classes included perfluorosulfonic acids, fluorotelomer alcohols, and fluorotelomer carboxylic acids.

Benefits and Practical Applications

This combined CIC and non-targeted LC-HRMS workflow offers:

• Sensitive, automated quantification of TOF and EOF for compliance monitoring.
• High extraction efficiency and minimal carryover for diverse FCM matrices.
• Extended profiling of unknown and non-extractable PFAS beyond targeted methods.

Future Trends and Opportunities

Key directions include:

• Integrating TOF screening with targeted, suspect, and non-targeted PFAS analyses for comprehensive exposure assessment.
• Optimizing extraction and combustion procedures to capture polymeric and volatile PFAS precursors.
• Establishing standardized protocols and shared spectral libraries to harmonize PFAS analysis across laboratories and regulatory bodies.

Conclusion

The developed CIC method reliably quantifies TOF and EOF in food contact materials, revealing that EOF constitutes a small fraction of total fluorine. Combined with non-targeted LC-HRMS, this approach uncovers diverse PFAS species missed by targeted assays, supporting regulatory compliance and deeper insight into PFAS contamination in FCM.

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