Determination of micro/nanoplastics on the surface of polystyrene lunch boxes by pyrolysis-gas chromatography/mass spectrometry combined with efficient magnetic capture by Fe3O4 nanoparticles

4.71–5.19 μg/box and 1.27–1.40 μg/box were detected for the migrated PS MPs and NPs. • Hydrophilic iron oxide nanoparticle was used to capture polystyrene nanoplastics. • Adsorption mechanism includes hydrogen bonding, coordination, electrostatic interaction. • Quantification of PS MPs and PS NPs from lunch boxes by Py-GC/MS. • The aging effect causing the decomposition of PS MPs into PS NPs. In this study, 1 μm glass fiber membranes were used to enrich polystyrene microplastics (PS MPs), and then hydrophilic iron oxide nanoparticle (n-Fe 3 O 4 ) was used to capture the residual polystyrene nanoplastics (PS NPs), primarily through hydrogen bonding, coordination, and electrostatic interactions. MPs on membranes and NPs captured by n-Fe 3 O 4 were respectively determined by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The method was verified by adding PS MNPs standard to ultrapure water. The detection limit of this method was 0.16 μg/cup for PS MPs and 0.03 μg/cup for PS NPs. The absolute recovery rates of MPs and NPs were 99 ± 2% and 89 ± 3%, respectively. The test results of three batches of PS lunch boxes showed that the content of PS MPs attached on surfaces was 6.79–12.30 μg/box, and the content of PS NPs was 0.51–0.96 μg/box. The migrated PS MPs and PS NPs were 4.71–5.19 μg/box and 1.27–1.40 μg/box respectively.