Amount of Fe determined by different techniques, and ID/IG Raman ratio of SWCNT samples purified with steam for a total cumulative time of 6 h.

This includes a single 6 h steam treatment (1 x 6 h) and also samples that were subjected to multiple shorter treatments, namely 6 times for 1 h (6 x 1 h), 3 times for 2 h (3 x 2 h) and 2 times for 3 h (2 x 3 h). SQUID values correspond to the 6 h points shown in Fig 1B).