Supercritical carbon dioxide is by far the most commonly used supercritical fluid. The unique solvent properties of supercritical carbon dioxide have made it a desirable compound for separating antioxidants, pigments, flavors, fragrances, fatty acids, and essential oils from plant and animal materials. In the supercritical state, carbon dioxide behaves as a lipollic solvent and so, is able to extract most nonpolar solutes. Separation of the carbon dioxide from the extract is simple and nearly instantaneous. Unlike liquid solvents, the dissolving power of supercritical carbon dioxide can be easily adjusted by slight changes in the temperature and pressure, making it possible to extract particular compounds of interest. With the addition of small amounts of polar co-solvents, even polar materials can be extracted. Additional advantages of carbon dioxide are that it is inexpensive, available in high purity.