Structures of water-containing or moist samples can be changed or destroyed when dried in the air or in a vacuum.

Critical point drying with the EM CPD300 is an optimal process for maintaining these structures.

The tangential forces of the interfacial tension that occur during drying between water and air are avoided by converting the liquid phase of CO2 into the gas phase without a phase transition. For this purpose, the solvent (e.g. water) may have to be replaced by acetone or ethanol, since this can then be replaced by CO2.