Assessment of nanoplastic extraction from natural samples for quantification purposes

•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.