ISO/TS 10868:2011 provides guidelines for the characterization of compounds containing single-wall carbon nanotubes (SWCNTs), using optical absorption spectroscopy.The purpose of ISO/TS 10868:2011 is to describe a measurement method for establishing the diameter, purity, and ratio of metallic SWCNTs to the total SWCNT content in the sample.The analysis of the diameter is applicable to a diameter range of 1 nm to 2 nm.