Overview
ISO 21363:2020 - Nanotechnologies: Measurements of particle size and shape distributions by transmission electron microscopy (TEM) - specifies a standardized workflow for capturing, measuring and analysing TEM images to obtain particle size and shape distributions at the nanoscale. The standard applies to discrete nano‑objects and to particles larger than 100 nm; the effective working range depends on the required measurement uncertainty and the performance of the TEM. ISO 21363:2020 was prepared by ISO/TC 229 and includes practical guidance, calibration requirements and case studies to support reproducible nanomaterials characterization.
Key topics and technical requirements
- Workflow stages: sample preparation, instrument factors, image capture, particle analysis, data analysis and reporting.
- Sample handling: guidance on representative sampling, dispersion methods to minimize agglomeration, and selection of mounting supports.
- Instrument calibration and setup: procedures for calibrating magnification and image scale, selection of TEM operating conditions and use of calibration standards.
- Image capture: recommendations on magnification, minimum particle area, frame selection and number of particles/micrographs needed for statistical validity.
- Particle analysis: manual and automated particle detection, treatment of touching particles, artefacts and contaminants, and individual particle vs. batch analysis.
- Descriptors: definitions and use of size descriptors (linear and areal), shape descriptors (elongation ratios, ruggedness) and bivariate descriptor analysis.
- Data analysis and uncertainty: fitting distribution models, assessing repeatability, intermediate precision and reproducibility, estimating measurement uncertainty for fitted parameters, and visualization tools (residuals, quantile plots).
- Reporting: minimum reporting elements, uncertainty statements and metadata to support comparability and traceability.
- Case studies: practical examples including spheroidal gold nanospheres, bimodal colloidal silica mixtures, gold nanorods/nanocubes, carbon black aggregates and titania aggregates.
Applications and users
ISO 21363:2020 is valuable for:
- Research laboratories and academic groups performing TEM-based nanoparticle characterization.
- Industrial quality control teams in nanomaterials manufacturing and coatings, catalysis, electronics and pharmaceuticals.
- Instrument manufacturers and service labs developing or validating TEM image analysis workflows.
- Regulatory bodies and standards organizations requiring traceable size/shape data for safety, compliance and labeling.
Keywords: ISO 21363:2020, transmission electron microscopy, TEM, particle size distribution, particle shape distribution, nanotechnologies, nanoparticles, measurement uncertainty, image analysis.
Related standards
- Developed under ISO/TC 229 (Nanotechnologies).
- References interlaboratory guidance such as VAMAS for ILCs and aligns with general metrology best practices for uncertainty, calibration and traceability.