Identification of chemicals in a polyvinyl chloride/polyethylene multilayer film by ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and their migration into solution

An ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) method was employed for chemical identification in a commercial polyvinyl chloride/polyethylene (PVC/PE) multilayer film. Over 30 chemicals from different layers (PE layer, PVC layer, and adhesive layer) of the film were identified and were classified into 6 groups, including antioxidants, plasticizers, slip agents, antistatic agents, adhesive components, etc. Special attention was placed on the analysis of some non-intentionally added substances and oligomers in adhesive. Based on the identification results, six additives (all from PE layer) were selected and their migration behaviors were investigated via one-sided contact migration test. The migration test was performed by exposing the PE side of the film to different simulating solutions (water, 40% ethanol, and 95% ethanol) at 40 degrees C, as well as recording the migration level as a function of time. No obvious migration was found into water for all additives, while the migration into 40% and 95% ethanol followed Fickian diffusion behavior, and could be described by Fick's diffusion equation. Diffusion coefficients derived from the equation were in a range of 10(-13) to 10(-10) cm(2)/s and were dependent on the type of additive and solution. (C) 2020 Elsevier B.V. All rights reserved.