How are residual solvents detected in printed food packaging?

Printed food packaging can retain solvents from the printing process. If those solvents are not properly removed before the packaging reaches the consumer, they can migrate into the food product and affect taste, smell, or safety. Residual solvent testing checks that solvent levels are within acceptable limits before packaging is released.

What are residual solvents in this context?

During printing, inks are dissolved or suspended in solvents that evaporate as the ink dries. Common solvent types include alcohols, ethers, acetates, and other volatile organic compounds. In most cases, the drying process removes the majority of the solvent. But traces can remain, particularly in multi-layer packaging, heavy ink coverage, or high-speed production where drying time is limited.

How GC detects them

Residual solvent testing uses headspace gas chromatography. A sample of the packaging material is sealed in a vial and heated. The volatile solvents trapped in or on the packaging move into the headspace above the sample. That headspace gas is then injected into the GC, which separates and quantifies the individual solvent compounds.

Headspace sampling is the right approach here because it isolates the volatile compounds without interference from the non-volatile packaging material itself. This gives cleaner results and better repeatability than dissolving or extracting the packaging.

The Ellutia 200 Series GC with FID handles this analysis. A headspace autosampler such as the EL2000H or EL2100H automates the process for batch testing.

When is this testing done?

Residual solvent testing is typically performed as part of quality control during or after packaging production. It may also be required by the brand owner or retailer as a condition of supply. Regulatory frameworks covering food contact materials set limits for specific solvents, and testing demonstrates compliance with those limits.

Want to set up Residual solvent testing for food packaging? Get in touch with the team.