Tracking of realistic nanoplastics in complicated matrices by iridium element labeling and inductively coupled plasma mass spectroscopy

Herein, we proposed a protocol to track realistic nanoplastics (NPs) by labeling them with an iridium-containing organic molecular agent (denoted as Ir) followed by inductively coupled plasma mass spectroscopy detection, as exemplified by polyethylene terephthalate (PET) NPs prepared from water bottles. The Ir showed satisfactory labeling stability in typical environmental and biological matrices. After 3d' s incubation, the leaching ratios were less than 3% in water, phosphate buffered saline, sea water, cell culture medium, artificial gastric juice, artificial intestinal fluid, sediment resuspension, and around 5% in fetal bovine serum. On this basis, in vivo distribution of PET NPs in mice was analyzed. The intravenously injected NPs widely distributed in liver, spleen, lung and kidney. Comparatively, NPs could hardly be detected in these organs after intragastric administration, suggesting that they could not penetrate the intestinal barriers. The temporal and spatial distribution of the NPs in an intertidal zone sediment resuspension model was also investigated. The NPs mostly deposited at the overlying deposit, implying the absorption-driven sinking behavior of NPs with natural organic matters. This work provided an effective way to quantitatively track realistic NPs, which could promote the understanding of the fate and effect of NPs in natural environments and organisms.