Analysis of Food Wrap Film Using Double-Shot Pyrolyzer ® Part 1 : Analysis with Evolved Gas Analysis (EGA)

Importance of the Topic

The thermal behavior of food wrap films directly impacts food safety and human health. Volatile compounds released from plastic films at elevated temperatures can migrate into food, potentially causing adverse effects upon prolonged exposure. Comprehensive thermal profiling of these materials is therefore essential for quality control, regulatory compliance, and consumer protection.

Objectives and Study Overview

This study applied Evolved Gas Analysis (EGA) using a Double-Shot Pyrolyzer® to determine the temperature ranges and chemical composition of volatiles released from common food wrap films. Four film types—polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), polyethylene (PE), and a polypropylene-nylon blend (PP+nylon)—were examined to establish their thermal release profiles and identify major volatile components.

Methodology

• Samples of each film (0.25 cm²) were subjected to a temperature ramp from 40 °C to 600 °C at 20 °C/min under helium flow.
• EGA capillary interface transferred evolved gases into a gas chromatograph–mass spectrometer system.
• Mass spectra were recorded over m/z 29–400 at 0.1 scan/s.

Instrumental Setup

• Pyrolysis furnace temperature: 40 °C to 600 °C at 20 °C/min
• Carrier gas: Helium at 50 kPa, split ratio ~1/50
• EGA capillary: 0.15 mm i.d., 2.5 m length (UAD™-25N)
• GC oven temperature: 300 °C
• Injection port temperature: 320 °C
• Mass spectrometer scan range: m/z 29–400, scan rate: 0.1 scan/s

Key Results and Discussion

• All films exhibited broad EGA peaks between 100 °C and 250 °C, corresponding to the release of plasticizers and residual monomers.
• PVDC showed initial volatile evolution followed by HCl elimination and subsequent polyene degradation at higher temperatures.
• PVC demonstrated a major HCl release event, with mass spectra indicating polyene chain formation.
• PE displayed thermal cracking products early in the ramp, reflecting its simpler hydrocarbon structure.
• PP+nylon presented distinct high-temperature decomposition peaks, attributable to both polypropylene and nylon components.
• Mass spectral data enabled tentative identification of fatty acid derivatives, epoxidized oils, aliphatic esters, and hydrocarbon resins as major additives.

Benefits and Practical Applications

This EGA approach provides rapid thermal fingerprinting for film quality assessment and additive characterization. It assists manufacturers in optimizing formulations to minimize volatile migration, supports regulatory evaluations of food contact materials, and enhances reliability in QA/QC laboratories.

Future Trends and Opportunities

Advancements may include coupling EGA with two-dimensional GC, high-resolution MS, and real-time data processing. Integration of chemometric and machine learning techniques can further improve compound identification and predictive modeling of migration behavior. Emerging pyrolysis interfaces and ambient ionization methods may enable in situ film analysis without extensive sample preparation.

Conclusion

The EGA method using Double-Shot Pyrolyzer® effectively profiles the thermal evolution of volatiles from various food wrap films. It delivers critical insights into additive release temperatures and chemical identities, supporting safer material design and compliance with food contact regulations.

References

Frontier Laboratories Ltd. Double-Shot Pyrolyzer® Technical Note PYA1-022E