Application of Pyrolysis-GC/MS to Food Contamination Analysis

Importance of the Topic

The rise of foreign matter in food products increases safety risks and regulatory pressures. Analytical techniques such as pyrolysis-GC/MS offer reliable identification of trace polymeric contaminants that are challenging for standard methods like FTIR.

Objectives and Study Overview

This study evaluates pyrolysis-GC/MS using a Shimadzu OPTIC-4 multimode inlet coupled to a GCMS-QP2020 NX system to characterize resin-based contaminants in food packaging materials.

Methodology

Sample Preparation:

• A section (~0.2 mg) of commercial food packaging was cut and placed into a DMI microvial.
• The microvial was inserted into the OPTIC-4 liner for pyrolysis.

Pyrolysis and GC/MS Conditions:

• Inlet temperature ramp: 40 °C to 600 °C at 60 °C/s, hold 3 min.
• Column: UA-5 MS/HT 30 m × 0.25 mm i.d., 0.25 μm film; helium carrier at 1.0 mL/min.
• GC oven: 40 °C (2 min) to 320 °C at 20 °C/min, hold 16 min.
• MS: Electron ionization, scan m/z 29–800.

Used Instrumentation

• Shimadzu GCMS-QP2020 NX
• OPTIC-4 multimode inlet
• UA-5 (MS/HT) capillary column

Main Results and Discussion

The pyrogram of the foreign matter showed regular hydrocarbon peaks characteristic of polyethylene (PE). Additional peaks were identified via NIST library as:

• Caprolactam – marker for polyamide (PA).
• Benzoic acid and 4-(vinyloxycarbonyl)benzoic acid – pyrolysis products of polyethylene terephthalate (PET).

These findings indicate that the contaminant was a composite resin containing PE, PA and PET layers.

Benefits and Practical Applications

Pyrolysis-GC/MS with a high-speed heating inlet provides:

• Qualitative identification of polymeric contaminants, including multilayer and trace-level resins.
• Rapid screening for contamination sources in food production lines.
• Support for quality control and root-cause analysis in food safety investigations.

Future Trends and Potential Applications

Advancements may include:

• Integration with automated sample handling for higher throughput.
• Quantitative pyrolysis-GC/MS methods for polymer contaminants.
• Combination with chemometric tools to classify unknown polymer blends.
• Extension to broader matrices such as pharmaceuticals and cosmetic packaging.

Conclusion

Pyrolysis-GC/MS using the OPTIC-4 inlet effectively identifies polymer-based contaminants in food packaging by generating distinct pyrolysis products. This approach supplements traditional spectroscopic techniques and enhances contamination analysis workflows.

Reference

(1) S. Tsuge, H. Ohtani, C. Watanabe: Pyrolysis-GC/MS Data Book of Synthetic Polymers – Pyrograms, Thermograms and MS of Pyrolyzers –, Elsevier, 1st Edition, 2011