Detection of 27 Residual Solvents in Food Packaging using Parallel Dual-Column Headspace Gas Chromatography

Significance of the Topic

Food packaging plays a critical role in protecting food from environmental contamination and extending shelf life. Residual solvents used in printing inks and packaging materials can migrate into food, affecting product quality and posing health risks. Regulatory bodies worldwide limit solvent residues in packaging to ensure consumer safety.

Objectives and Overview

This study demonstrates the application of an automated parallel dual-column headspace gas chromatography–flame ionization detection (HS-GC-FID) method for simultaneous confirmation and quantitation of 27 residual solvents in food packaging materials. The parallel column configuration provides improved separation and confirmation capabilities compared to single-column analyses.

Applied Instrumentation

• Shimadzu HS-20 Headspace Autosampler
• Shimadzu GC-2010 Plus Gas Chromatograph with FID
• SH-Rtx-VMS column (60 m × 0.25 mm ID, 1.4 µm df)
• SH-Rxi-1MS column (60 m × 0.25 mm ID, 1.0 µm df)
• Twin-line kit for parallel column switching

Methodology

Packaging samples (100 cm2) were cut into small pieces and placed in 20 mL headspace vials without further pretreatment. A 0.02% solvent standard mixture (equivalent to 1 µg of each solvent) was prepared in ethyl acetate (methanol for ethyl acetate quantitation). Headspace conditions included 120 °C oven temperature and 50 kPa pressurizing pressure with 15 min equilibration. GC oven program started at 35 °C (10 min), ramped to 90 °C at 20 °C/min (5 min), then to 180 °C at 20 °C/min (7 min). FID settings: 200 °C, H2 flow 40 mL/min, air flow 400 mL/min, N2 make-up 30 mL/min. Helium carrier gas at 25 cm/s linear velocity.

Main Results and Discussion

The comparison of diluents showed that ethyl acetate minimized peak tailing for polar analytes, while methanol was used for ethyl acetate quantitation. Dual-column analysis resolved most of the 27 solvents; overlapping pairs such as 1-butanol/methoxypropanol and m-/p-xylene were handled by confirmation on the alternate column. Signal-to-noise ratios exceeded 100 for 26 solvents at 1 µg, indicating detection capability below 0.1 mg/m2. Repeatability (%RSD) ranged from 1 to 3%. Quantitation of real packaging samples revealed toluene as the predominant residual solvent, reaching up to 22.2 µg/100 cm2 (2.2 mg/m2).

Benefits and Practical Applications of the Method

• No tedious sample preparation due to automated headspace sampling
• Parallel dual-column approach enhances separation and confirmation confidence
• High sensitivity and precision support regulatory compliance
• Suitable for routine QA/QC of food packaging materials

Future Trends and Opportunities

Further integration of mass spectrometric detection could expand analyte scope and selectivity. Miniaturized and portable HS-GC systems may enable on-site packaging verification. The method can be adapted for other volatile contaminants, supporting broader food safety and environmental monitoring applications. Increased automation and data integration with laboratory information management systems (LIMS) will enhance throughput and traceability.

Conclusion

The parallel dual-column HS-GC-FID technique provides a robust, sensitive, and efficient approach for detecting and quantifying a broad range of residual solvents in food packaging materials. The method offers regulatory compliance, high throughput, and reliable confirmation of analyte identity.

References

1. Seo I, Shin HS. Food Science and Biotechnology. 2010;19(6):1429–1434.
2. Korea Ministry of Food and Drug Safety. Standards and Specifications for Food Utensils, Containers and Packages. March 2015.
3. ASTM F1884-04(2011). Standard Test Method for Determining Residual Solvents in Packaging Materials. ASTM International; 2011.