Analysis of Vinylidene Chloride in Polyvinylidene Chloride Plastics by GC

Significance of the Topic

The presence of residual vinylidene chloride monomer in polyvinylidene chloride (PVDC) food packaging films raises concerns for consumer safety due to potential adverse effects on the liver and kidneys. Reliable quantification of this monomer supports regulatory compliance under Japan’s Food Sanitation Act and contributes to quality assurance in the packaging industry.

Objectives and Study Overview

This study demonstrates a headspace gas chromatography method with flame ionization detection (GC/FID) for quantifying vinylidene chloride in PVDC plastic films. It aims to validate sample preparation, chromatographic conditions, and data evaluation to ensure monomer levels do not exceed the regulatory limit of 6 µg/g.

Sample Preparation and Analysis Methodology

• Fragment Preparation: A 0.5 g piece of PVDC film is weighed and placed in a headspace vial.
• Solvent Addition: 2.5 mL of N,N-dimethylacetamide is added to extract the monomer and the vial is sealed.
• Standard Solution: 50 µL of a 60 µg/mL vinylidene chloride stock solution is mixed with 2.5 mL of N,N-dimethylacetamide to prepare the calibration standard.
• Headspace Sampling: Both sample and standard vials are heated at 90 °C for 60 minutes to equilibrate.
• Injection and Detection: A 0.5 mL aliquot of headspace gas is injected into the GC/FID system. Retention times are compared to confirm peak identity and peak areas are used for quantification.

Instrumentation Used

• Headspace Sampler: TurboMatrix HS-40
• Gas Chromatograph: GC-2010 Plus AF
• Column: CP-PoraBOND Q (25 m × 0.25 mm I.D., df = 3 µm porous styrene-divinylbenzene)
• Detector: Flame Ionization Detector (FID)

Main Results and Discussion

Chromatograms show vinylidene chloride eluting around 9 minutes. The sample film’s peak area is consistently lower than that of the standard, confirming residual monomer levels below the 6 µg/g threshold. Method stability is supported by clear peak resolution and reproducible retention times.

Benefits and Practical Applications

This headspace GC/FID approach delivers a simple, reproducible, and sensitive test for monitoring vinylidene chloride in food packaging materials. It enables manufacturers and regulatory bodies to perform routine quality control and ensures consumer safety through compliance verification.

Future Trends and Opportunities

• Integration with automated sample handling to increase throughput.
• Exploration of more selective detectors or tandem MS for enhanced sensitivity.
• Extension of the method to other residual monomers and polymeric matrices.
• Development of miniaturized headspace systems for on-site screening.

Conclusion

The presented headspace GC/FID method effectively quantifies residual vinylidene chloride in PVDC films, meeting regulatory requirements while providing robust performance for routine analysis. Its simplicity and reliability make it well suited for adoption in quality assurance laboratories.

References

• Ministry of Health, Labour and Welfare Notification No. 201. Food Sanitation Act – Section 3: Implements, Containers, and Packaging in the Standards and Criteria for Food and Food Additives, etc., March 31, 2006.