Sublimation consists of the evaporation of a solid from a hot surface and its subsequent condensation on another surface at a lower temperature.
Depending on the nature of the solid, sublimation can occur at atmospheric pressure or under vacuum.
It is a very effective technique for the purification of solids at the microscale since it involves a minimum loss of substance and the elimination of solvent residues that may be trapped in the solid with better results than in the case of conventional recrystallization.
The efficiency of the sublimation process depends on both the vapor pressure of the solid to be purified and the impurities to be removed.
There are many ways to sublimate a solid at microscale, ranging from the use of devices specifically designed for this purpose (sublimators), to the adaptation of the material available to perform this operation.
In this second case, the use of a Kitasato, a centrifuge tube, with a rubber cone, to which a vacuum is applied, can be an effective solution.
The centrifuge tube is filled with ice or dry ice at a distance of about 2 cm from the bottom of the Kitasato and the Kitasato is placed over a heat source.