We describe the sublimation property of a flavin molecule as a solution to the surfactant residue problem of single-walled carbon nanotubes. Thermogravimetric analysis, UV-vis spectroscopy, and NMR indicate our flavin has sublimability. The saturated vapor pressure of the flavin was calculated to be 0.08 Pa at 250 degrees C. Careful vacuum and temperature control or further modification of the molecular structure is necessary to avoid competing thermal reactions.