Carbon dioxide (CO2) is the most widely used supercritical fluid. This is because CO2 is cheap, chemically inert, non-toxic, non-flammable and readily available at high purities and at low costs. Besides, the critical point of CO2 is easily accessible (critical temperature 31°C and critical pressure 74 bar) allowing the fluid to be used at mild conditions of temperatures (40-60°C) without leaving harmful organic residues. Due to its interesting properties Supercritical CO2 can be described as a "green" solvent