Paper on the developed characterisation methods for SMPs (< 10 μm) and NPs (< 0.1 μm), and in terms of: (i) chemical identity of the SMPs/NPs polymer type; (ii) physical particle characterisation and quantification, size distribution and particle morphologies; and (iii) quantification of the mass fraction in complex matrices. Uncertainty evaluation and traceability statements will be included

Reliable reference and quality control materials are essential for advancing the measurement and risk assessment of nanoplastics. However, materials with physicochemical properties comparable to those of real environmental and food contaminants are still lacking. Within this work, presented in the paper “Multiparameter characterisation of a nano-polypropylene representative test material with fractionation, light scattering, high-resolution microscopy, spectroscopy, and spectrometry methods”, we describe the development and comprehensive characterisation of a polypropylene nanoplastic material produced through a top-down mechanical fragmentation process. The material is homogeneous, stable in suspension, and representative of environmental nanoplastics.A wide range of analytical techniques — including AF4, cFFF, PTA, (MA)DLS, MALS, SEM, AFM, TEM, STEM, EDS, Raman, ICP-MS and py-GC/MS — were employed to determine its particle size and distribution, particle number concentration, polymer identity, mass fraction, and inorganic impurity content. Results show a broad size distribution (50–200 nm), consistent polypropylene composition with signs of surface oxidation, and trace levels of inorganic impurities. The study demonstrates how complementary measurement approaches can be combined to improve the reliability, uncertainty evaluation, and traceability of nanoplastics characterisation.This work directly contributes to the PlasticTrace deliverable “Paper on the developed characterisation methods for SMPs (<10 μm) and NPs (<0.1 μm)”, addressing the chemical identification, physical characterisation, and quantification of nanoplastic materials, and providing a reference framework for harmonised and comparable measurements across laboratories. “The project 21GRD07 PlasticTrace has received funding from the European Partnership on Metrology, co-financed from the European Union’s Horizon Europe Research and Innovation Programme and by the Participating States.”• Funder name: European Partnership on Metrology• Funder ID: 10.13039/100019599• Grant number: 21GRD07 PlasticTrace