Evaluating Phthalate Contaminant Migration Using Thermal Desorption–Gas Chromatography–Mass Spectrometry (TD–GC–MS)

Abstract

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.

Transfer of Frictional Contact Derived Phthalates from Pad Surface Enhances Dermal Exposure

“…It is well known that DnBP/small molecules diffuse faster than DEHP/large molecules; e.g., the measured mass transfer coefficient over the surface of vinyl flooring and crib mattress covers for DnBP (2.54 × 10 –4 m s –1 at 25 °C) was greater than that for DEHP (2.10 × 10 –4 m s –1 at 25 °C) . In addition, fictional heating due to mechanical motion on the pad surface resulted in elevated surface microfilm temperatures, enhancing the diffusion transfer within the pad matrix and/or pad interface. , Scraping in the pad surface that originated from frictional motion also dictates the mechanism of mass transfer under dry friction. For instance, the net/pocket micro-surface structure of medical gauze had greater accumulated efficiency for DEHP (Figures S8 and S9c).…”

“…20 In addition, fictional heating due to mechanical motion on the pad surface resulted in elevated surface microfilm temperatures, enhancing the diffusion transfer within the pad matrix and/or pad interface. 20,32 Scraping in the pad surface that originated from frictional motion also dictates the mechanism of mass transfer under dry friction. For instance, the net/pocket micro-surface structure of medical gauze had greater accumulated efficiency for DEHP (Figures S8 and S9c).…”

Phthalate migration and its effects on poly(vinyl chloride)-based footwear: pathways, influence of environmental conditions, and the possibility of human exposure

“…Moreover, the loss of phthalates through migration is one of the most dominant adverse factors contributing to the aging of exible PVC, limiting its applications in many important elds. 2,26 Phthalates can also be released from so PVC by surface contact, and the release rate increases with temperature, 27 mechanical pressure, 28 and under dynamic conditions. 25 In the case of footwear with PVC soles, the phthalate might migrate from the PVC sole to the insole (leather or polymeric) and come into direct contact with the user.…”