Waters' Supercritical Fluid Extraction (SFE) Systems extract chemical compounds using supercritical carbon dioxide instead of an organic solvent. The supercritical fluid state occurs when a fluid is above its critical temperature (Tc) and critical pressure (Pc), when it is between the typical gas and liquid state. Manipulating the temperature and pressure of the fluid can solubilize the material of interest and selectively extract it. The sample is placed in an extraction vessel and pressurized with CO2 to dissolve the sample. Transferred to a fraction collector, the contents are depressurized and the CO2 loses its solvating power causing the desired material to precipitate. The condensed CO2 can be recycled.