Characterizing unknowns in food packaging using GC Orbitrap Mass Spectrometry

Importance of the Topic

Packaging preserves food from microbial and chemical hazards. Chemical migration from packaging materials can pose health risks. Identifying non-intentionally added substances (NIAS) helps regulators and manufacturers assess safety and ensure product quality.

Objectives and Overview of the Study

This study aimed to profile unknown compounds in food packaging materials using full-scan high-resolution GC Orbitrap mass spectrometry. Key goals included rapid detection of known and unknown migrants, confident elemental composition assignment, and structural elucidation of compounds with low or no library matches.

Methodology and Instrumentation Used

• Sample extraction: Hexane–acetone (1:1) liquid extraction of tin can coating, room temperature, 16 hours, concentration to 1 mL.
• Instrument: Hybrid quadrupole-Orbitrap GC mass spectrometer operated in electron ionization (EI) full-scan at 120,000 FWHM and positive chemical ionization (PCI) with methane reagent gas.
• GC system: TRACE 1310 GC with TRACEGOLD TG-5SilMS capillary column (30 m × 0.25 mm × 0.25 µm) and TriPlus RSH autosampler.
• Data processing: TraceFinder software for accurate mass deconvolution and library matching; MassFrontier for structural interpretation; NIST 2014 library for initial identification.

Main Results and Discussion

• 961 deconvoluted features detected above S/N 100:1 threshold in full-scan EI data.
• High confidence identification of known migrants using combined spectral matching index and high-resolution filtering (HRF).
• Six major unknown peaks (RT ~30.6 to 53.2 min) lacked library matches. PCI data revealed quasi-molecular [M+H]+ and adduct ions enabling elemental formulas with <1 ppm mass error.
• Isomeric forms detected for some compounds; MS/MS experiments provided fragment ions and isotopic patterns for structural proposals.
• Automation in TraceFinder simplified peak extraction and formula assignment, reducing manual interpretation time.

Benefits and Practical Applications of the Method

• Non-target full-scan approach captures broad chemical information with minimal sample preparation.
• High mass accuracy and resolution facilitate rapid identification and reduce false positives.
• Combined EI and PCI modes improve detection of molecular ions and fragment coverage.
• Software-assisted workflows accelerate unknown identification and structural elucidation critical for compliance and safety assessments.

Future Trends and Potential Applications

• Expansion of high-resolution mass spectral libraries for NIAS and packaging-related compounds.
• Integration of machine learning algorithms to predict compound structures and migration behavior.
• Development of standardized non-target workflows for regulatory screening of food contact materials.
• Coupling GC Orbitrap platforms with tandem techniques for multi-dimensional analysis of complex migrants.

Conclusion

The GC Orbitrap platform combined with advanced data processing provides a robust workflow for comprehensive profiling of food packaging migrants. The high resolution and mass accuracy enable the confident assignment of elemental compositions and structural elucidation of unknowns. This approach supports regulatory compliance and helps manufacturers minimize health risks associated with packaging materials.

References

1. L. L. Katan (ed) Migration from Food Contact Materials, Blackie Academic and Professional, Glasgow, UK, 1996.
2. K. A. Barnes, C. R. Sinclair, D. H. Watson Chemical Migration and Food Contact Materials, Woodhead Publishing, 2006.
3. Thermo Fisher Scientific AN10492 Chemical profiling and differential analysis of whiskies using Orbitrap GC-MS, Thermo Fisher Scientific, Runcorn, UK.