Many properties of single wall carbon nanotubes (SWNTs) are unique and advantageous. The electrical, thermal, and strength properties of SWNT are highly desirable for many applications. To take advantage of these properties it is necessary to remove the impurities that are inevitability produced during the growth of the nanotubes. High gradient magnetic separation techniques have been used to separate the magnetic catalyst particles from the nanotubes. Even if all the impurities were removed there would still be many different types of SWNTs in a sample. For the first time, different types of SWNTs have been observed acting as individual chemical species by changing the pH of surfactant stabilized suspensions of SWNTs. In the future, one can expect this scheme to play an important role in the separation of SWNTs by type.