The International Organization for Standardization (ISO) has published standard ISO/TS 11308:2020, “Nanotechnologies — Characterization of carbon nanotube samples using thermogravimetric analysis.”  The standard provides guidelines for the characterization of carbon nanotube (CNT)-containing samples by thermogravimetric analysis (TGA), performed in either an inert or oxidizing environment.  The standard offers guidance on the purity assessment of the CNT samples through a quantitative measure of the types of carbon species present, as well as the non-carbon impurities (e.g., metal catalyst particles) within the material.  ISO notes that this technique provides a qualitative assessment of the thermal stability and homogeneity of the CNT-containing sample.  ISO states that additional characterization techniques are required to confirm the presence of specific types of CNT and to verify the composition of the metallic impurities present.