Supercritical fluid extraction (SFE) is a technique that uses supercritical fluid as an extraction medium. Methods employing supercritical carbon dioxide as an extraction medium have many advantages and are used in a variety of fields. Extraction by means of supercritical carbon dioxide can improve efficiency, including shorter extraction times and simplified procedures, when compared with extraction techniques that employ organic solvents. At the same time, it offers easier solvent elimination and concentration procedures.
Since its critical temperature is a low 31ºC, SFE enables extraction at or near room temperatures or in a carbon dioxide atmosphere devoid of oxygen. This makes it a technique that can be used for materials that exhibit temperature instability or constituents that are susceptible to oxidation. In addition, it has received a great deal of attention as an environmentally friendly extraction technique that does not use hazardous organic solvents, as has been advocated by the green chemistry movement in recent years.
Applications for SFE include the extraction of active constituents, including various flavors and medicinal constituents from natural products, docosahexaenoic acid (DHA), advanced unsaturated fatty acids and fatty esters such as eicosapentaenoic acid (EPA), fat-soluble vitamins, and pharmaceuticals, as well as the elimination of unwanted constituents, such as decaffeination and desolvation within tablets. It also can be applied to the preprocessing of analysis samples, including HPLC and GC.