Separation and identification of nanoplastics in tap water

Microplastics pollution in freshwater has attracted global attentions, but when microplastics are broken into nanoplastics, they may present higher toxicity mainly due to their greater potential to cross biological membranes. So far almost no work has been done on the separation and identification of nanoplastics in tap water. Herein we removed large particles from tap water by 0.45 μm filter and then sequentially screened nanoparticles in filtrate by Anopore with pore size of 200, 100, and 20 nm, the most frequent particle sizes of which concentrate at 255 nm, 148 nm, and 58 nm, respectively. Based on characterization of FTIR, AFM-IR and Pyr-GC/MS, the polymers were identified to be polyolefins, polystyrene, polyvinyl chloride, polyamide, and some plastic additives. The abundance of nanoplastics with the most frequent particle sizes in range of 58-255 nm was 1.67-2.08 μg/L in tap water. This work provides a feasible method for separation and identification of nanoplastics in tap water, and manifests the existence of nanoplastics, which poses a potential threat to the health of residents.