Optimization of analytical method for volatile organic compounds released from plastics and their emission characteristics by selected-ion flow tube mass spectrometry.

Abstract

While plastics are indispensable to our lives, they are known to emit harmful chemicals which can cause devastating effects to the environmental and human health. With the increasing concerns for global air pollution and climate change, the potential contributions of volatile organic compounds (VOCs) released from plastics have also been receiving increasing attention in recent years. Here, we developed and optimized a method for characterization of VOCs emitted from plastics. Using a selected-ion flow tube mass spectrometry (SIFT-MS), VOCs emissions were measured in real-time and data interpretations were performed using multivariate analysis. Expanded polystyrene (EPS), polypropylene (PP), high- and low-density polyethylene (HDPE and LDPE) and polyethylene terephthalate (PET) pellets were selected by their dominance as marine plastic debris. Emission characteristics of VOCs from selected polymers were monitored according to temperatures from 30℃ to 80℃. The emission of VOCs significantly increased with increasing temperatures for all plastic types, but varied in the order of LDPE, HDPE, PP, EPS, and PET. Partial least squares (PLS) analysis showed significant differences in compound group types, especially for compounds with relatively high molecular weight when heated at 80℃. The less-distinct differences in clustering of VOCs emitted at temperatures below 80℃, especially 60℃, were likely represented by additives and residuals during plastic production while VOCs emitted with temperatures above 80℃ were likely due to thermal degradation of polymers. The emitted compounds showed the highest mass concentrations with hydrocarbons such as alkane and alkene followed by monomers of each plastic type. These results suggested that the temperature threshold for VOCs emissions from residual materials and thermal degradations needs to be considered as one of the main factors for the analysis of VOCs from plastic debris.