Evaluation of heavy metal migration from different types of plastic food packaging materials into aqueous simulants using ICP-MS

Significance of the Topic

Plastic materials are extensively used in food packaging, yet they can release trace heavy metals into food simulants, potentially posing health risks. Accurate assessment of this migration is essential for regulatory compliance and consumer safety.

Objectives and Overview of the Study

This research investigates the release of 14 metallic elements from three common plastic packaging types – polystyrene container, polypropylene container, and polyethylene film – into three aqueous food simulants: deionized water, 2% nitric acid, and 3% acetic acid. The study aims to quantify elemental migration, examine the impact of contact time, and compare results against EU regulation limits.

Methodology and Instrumentation

Sample preparation involved immersing 0.5 g of each plastic into 40 mL of simulant at room temperature for up to 72 hours. After exposure, aliquots were acidified and diluted prior to analysis. The method validation included:

• Multi-element calibration up to 50 ppb or 200 ppb for targeted metals with internal standard correction
• Limit of detection and quantification determination based on blank variability
• Spike recovery tests at 10 ppb with repeatability checks (n=3)

Instrumentation Used

Analyses were performed on a Shimadzu ICPMS-2030 equipped with a mini-torch, AS-10 autosampler, nebulizer 07UES, and cyclone chamber. Key operating conditions:

• RF power 1.20 kW; sampling depth 6 mm
• Argon plasma, auxiliary, and carrier flows set at 8.0, 1.10, and 0.70 L/min respectively
• Helium collision cell mode for most analytes; cell gas flow 6.0 mL/min
• Internal standards Sc, Y, Rh, and Bi introduced online

Main Results and Discussion

Calibration curves showed excellent linearity (r > 0.9999), with LODs in sub-ppb range for toxic elements. Recoveries ranged from 87 % to 116 %, and RSDs were generally below 3 %. Migration results in 3 % acetic acid after 72 h revealed:

• PE film leached highest levels of zinc (685.5 µg/kg), iron (142.5 µg/kg), and aluminum (135.5 µg/kg)
• PS and PP containers released primarily aluminum, zinc, and copper, with aluminum up to 71.4 µg/kg
• Toxic arsenic and lead were detected at low concentrations (0.06–0.48 µg/kg and 0.19–3.27 µg/kg respectively)
• Cadmium migration was only observed from PE film (0.26 µg/kg)

All measured values were below EU No 10/2011 limits. Extended contact time from 1 h to 72 h significantly increased metal migration, and acetic acid simulant produced higher leaching than water or nitric acid.

Benefits and Practical Applications

The developed ICP-MS method offers high sensitivity, accuracy, and reproducibility for multi-element analysis. It supports quality control in food packaging production, regulatory compliance testing, and risk assessment in food safety laboratories.

Future Trends and Applications

Advancements may include:

• Integration with chromatographic separation for complex matrices
• Miniaturized and portable ICP-MS systems for in-field testing
• Isotopic or speciation analysis to distinguish metal sources
• Extension to non-aqueous simulants and real food samples
• Stricter regulatory requirements driving method refinement

Conclusion

An ICP-MS procedure was established to quantify heavy metal migration from plastic food packaging into standard simulants. The method demonstrated low detection limits, robust validation, and compliance with EU regulations. Metal release varied by polymer type, simulant, and exposure time, emphasizing the need for targeted quality control and safe packaging design.

Reference

1. Zhanhua Dong, Lixin Lu, Zhigang Liu, Yali Tang, Jun Wang, Migration of Toxic Metals from Ceramic Food Packaging Materials into Acid Food Simulants, Mathematical Problems in Engineering 2014, Article ID 759018.
2. Commission Regulation (EU) No 1935/2004 & No 10/2011 on plastic materials intended to come into contact with food, OJ L 12, 15.1.2011, p. 1.