This document provides guidelines for characterizing samples containing SWCNTs using ATG in air. It provides guidance on evaluating the purity of SWCNT samples by means of quantitative measurement of the levels of non-carbonaceous impurities (i.e. metal catalyst, in the material). Additionally, this technique can provide a qualitative assessment of thermal stability and homogeneity of the sample containing SWCNTs. To confirm the presence of the single-walled carbon nanotubes and to verify the composition of the metallic impurities, other characterization techniques are necessary.