The specific technical objectives of the project are to: Develop traceable measurement and calibration protocols to measure particle number concentrations in liquid suspension with a target relative uncertainty of better than 10 % for spherical particles in the size range 1 nm to 1000 nm. Develop methods to quantify the number concentration of particles in partially agglomerated or aggregated states within a liquid suspension of otherwise monodisperse primary particles and the ability to measure number concentration of particles with a non-spherical shape. Develop standard procedures to traceably measure the chemical composition and thickness of the nanoparticle shell, both to within 10 % uncertainty. Conduct two inter-laboratory studies to establish a good practice guide for industry and thereby establish laboratory-scale methods to enable valid, routine monitoring and quality control of particle concentration and surface chemistry for nanoparticle-based formulations and products. Engage with industry that manufactures and or / exploits nanoparticles in order to facilitate the uptake of the technology and measurement infrastructure developed by the project, to support the development of new, innovative products, thereby enhancing the competitiveness of EU industry. The project additionally includes an investigation of the effect of particle shape upon number concentration measurements for nanoparticles in a liquid suspension. The importance of non-spherical particles in innovative applications is growing and this additional activity addresses this emerging need. The results of this project will provide input to existing standards and stimulate the creation of new international standards which will enable both the concentration and surface chemistry of particles to be measured in a consistent and comparable manner. The partners will disseminate the results to a range of technical committees and standards bodies (e.g. ISO/TC 229, ISO/TC 201, ISO/TC 202, ISO/TC 24/SC 4).