Abstract
Highlights: • Evaluation of nanoplastic retention capacities during membrane filtration. • Polystyrene nanospheres, selected as model nanoplastics, were used to monitor the losses. • Polystyrene nanospheres are strongly retained on polymer-based membranes or glass fiber filters. • Plane inox grids have very low retention capacities. • Monitoring of the nanometric fraction during river sample by nanotracking analysis.Abstract: Plastic pollution poses an increasing threat to the whole ecosystem. Scientists recently realized that this pollution also occurs at the nanoscale. Nanoplastic monitoring is a real challenge and published data are scarce. Above the use of appropriate analytical instrument, one main obstacle is to quantitatively isolate the nanoplastic from larger particles in real samples. We propose a method based on the monitoring of polystyrene nanospheres following the polystyrene intrinsic fluorescence to assess the losses. Polymer-based membranes were tested for filtration, ultrafiltration and dialysis; important losses were observed. The isolation of the colloidal fraction is proposed using stainless steel grid with reduction of the losses. The ability of glass fiber filters to trap the nanoplastic was also evaluated as a mean to transfer the particle to the analytical instrument. As an illustration, a river sample was processed with the recommended protocol and the colloidal content monitored by nanoparticle tracking analysis. As a conclusion, we insist on the fact that it is absolutely necessary to evaluate nanoplastic extraction efficiencies for quantification purposes and we give recommendations to limit losses.