This study describes a methodology for evaluating regulatory levels of phthalate contamination. By collecting experimental data on short-term phthalate migration using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS), the migration of di(2-ethylhexyl) phthalate (DEHP) from polyvinyl chloride (PVC) to polyethylene (PE) was found to be expressed by the Fickian approximation model, which was originally proposed for solid (PVC)/liquid (solvent) migration of phthalates. Consequently, good data correlation was obtained using the Fickian approximation model with a diffusion coefficient of 4.2 × 10-12 cm²/s for solid (PVC)/ solid (PE) migration of DEHP at 25 °C. Results showed that temporary contact with plasticized polymers under a normal, foreseeable condition may not pose an immediate risk of being contaminated by phthalates at regulatory levels. However, as phthalates are small organic molecules designed to be dispersed in a variety of polymers as plasticizers at a high compounding ratio, the risk of migration-related contamination can be high in comparison with other additives, especially under high temperatures. With these considerations in mind, the methodology for examining regulatory levels of phthalate contamination using TD-GC-MS has been successfully demonstrated from the viewpoint of its applicability to solid (PVC)/solid (PE) migration of phthalates.
Keywords: Fick’s law; additives; contaminant; gas chromatography–mass spectrometry; phthalate migration; plasticized PVC; plasticizer; solid/solid interface; thermal desorption.