Migration of toluene through different plastic laminated films into food simulants

Laminated films are generally prepared from two or more monolayer films bonded using adhesives, such that the printing ink and adhesives are located between the films. Although the organic solvents in the adhesive, printing ink, and diluter are not in direct contact with the food, they may migrate through the films under certain conditions, potentially threatening human health. In this study, gas chromatography was used to analyze the migration rate of residual toluene from laminated films into four food simulants, namely isooctane, 50% ethanol, 3% acetic acid, and 10% ethanol. The effect of different parameters on toluene migration was characterized for internal films prepared with either low density polyethylene (LDPE) or cast polypropylene (CPP). The migration rate varied markedly with the temperature, with higher temperatures leading to accelerated migration into the simulants. The toluene levels in the simulants plateaued after a certain time period. Isooctane was the simulant into which toluene migrated the fastest. CPP films proved more efficient barriers than those prepared with LDPE. Within a certain range, increasing the initial toluene content in the laminated films had almost no observable effect on its migration rate.