Analysis of food wrappings with Double-Shot Pyrolyis-GCMS

Importance of the topic

Food packaging materials are in direct contact with consumables and can release volatile additives or degradation products that pose health risks over time. Ensuring the thermal stability and chemical safety of these polymers is essential for consumer protection and regulatory compliance.

Objectives and overview of the study

This application note introduces a streamlined analytical workflow using Double-Shot Pyrolysis-GC/MS to characterize food wrapping polymers. The primary goal is to simplify sample preparation, determine optimal analysis temperatures, and identify both additives and polymer decomposition products in a single approach.

Methodology and instrumentation

Key analytical steps:

• Evolved Gas Analysis (EGA): A linear temperature ramp is applied to the material, and the mass spectrometer continuously records released compounds. Thermograms reveal temperatures at which low-molecular-weight additives evaporate and the polymer matrix decomposes.
• EGA-Heart-Cut Pyrolysis-GC/MS: Selected temperature zones from EGA are trapped (“dark cut”) at the head of the GC column, then separated and identified by GC/MS.
• Database-assisted polymer identification: The F-Search software database matches pyrolysis fragment spectra to known polymers and co-polymers.

Instrumentation:

• Double-Shot Pyrolyzer for sequential EGA and pyrolysis.
• Gas chromatograph with heart-cut interface.
• Quadrupole mass spectrometer for compound identification.
• F-Search spectral database.

Main results and discussion

1. Poly(vinylidene chloride) (PVDC) analysis:

• Zone A (low temperature): Detection of butanol, tributyl aconitate and tributyl acetylcitrate softener.
• Zone B (intermediate temperature): Major tributyl acetylcitrate signals, minor tributyl aconitate and HCl (PVDC degradation product).
• Zone C (high temperature): Dominance of HCl, benzene and chlorinated aromatics from PVDC chain breakdown.

2. Polypropylene/Nylon blend packaging:

• Zone A: Acetic acid and fatty acid esters used as plasticizers.
• Zone B: Olefinic hydrocarbons (C6, C9, C12, C15) from PP pyrolysis and ε-caprolactam monomer from Nylon-6.

3. Polymer identification:

• F-Search database enabled rapid confirmation of PP based on characteristic pyrolysis fragment spectra.

Benefits and practical applications of the method

• Minimal sample preparation: direct analysis of small sample sizes without solvent extraction.
• Comprehensive profiling: simultaneous detection of additives, monomers and degradation products.
• High throughput: rapid temperature screening followed by targeted GC/MS improves efficiency in QA/QC labs.
• Regulatory support: precise thermograms and compound identification aid compliance with migration limits.

Future trends and utilization possibilities

Advancements may include integration with high-resolution mass spectrometry for improved structural elucidation, expanded spectral libraries covering emerging biopolymers, and automated workflows for real-time monitoring of packaging streams. Coupling with regulatory databases could further streamline safety assessments.

Conclusion

Double-Shot Pyrolysis-GC/MS with EGA-Heart-Cut offers a versatile, fast and reliable approach for characterizing food packaging materials. By eliminating extensive extraction steps and leveraging targeted temperature cuts, this method delivers detailed insights into both additives and polymer degradation products, supporting robust food safety and quality assurance protocols.