Analysis of micro/nanoplastics on the surface of polystyrene foam lunch boxes by pyrolysis-gas chromatography/mass spectrometry

Abstract

In this work, membrane filtration and ultrafiltration centrifugation were used to separate and concentrate micro/nanoplastics attached on the surface of polystyrene (PS) foam lunch boxes. A pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) method was established to determine the content of PS micro/nanoplastics, expressed as a mass concentration, which was more suitable for the data comparison. The inner surface of a PS foam lunch box was rinsed with ultrapure water, and the PS microplastics in the rinse water were collected through a glass fiber membrane with pore size of 1 μm. Subsequently, an ultrafiltration centrifuge tube (100 kDa) was used to filter the filtrate again to collect the PS nanoplastics. The obtained PS micro/nanoplastics were qualitatively and quantitatively analyzed by Py-GC/MS. It was found that 8.52–11.43 μg/box of PS microplastics and 0.104–0.154 μg/box of PS nanoplastics were attached on the surface of three batches of PS foam lunch boxes. The detected mass of microplastics was 55.3–109.9 times that of nanoplastics. The particle number of PS nanoplastics is estimated about 1.21 × 10^7 and 1.79 × 10^7 items/box. The method validation showed that the absolute recoveries of PS microplastics and nanoplastics were 91.4 ± 11.3 % and 61.7 ± 7.5 %, respectively. The results demonstrated that the proposed method can be applied to the qualitative and quantitative analysis of micro/nanoplastics on the surface of food contact materials, providing references for the safe use of food contact materials.