Supercritical Fluid Extraction (SFE) is the process of separating one component (the extractant) from another (the matrix) using supercritical fluid, such as CO2, as the extracting solvent. SFE can be used as a sample preparation step prior to further analysis by other techniques, or on a larger scale to either strip unwanted material from a product or collect a desired product. With cannabis, the goal is typically to collect CBD, THC, terpenes and other compounds while stripping away unwanted residues, like pesticides, chlorophyll and waxes, and leaving behind the biomass.
SFE with CO2 is rapid, simple and inexpensive; provides quantitative recovery of analytes without loss or degradation; yields a solution of the analyte that is sufficiently concentrated to permit the final measurement to be made without the need for concentration; and generates little or no laboratory wastes that require expensive disposal. CO2 is easy to remove simply by reducing the pressure, leaving almost no trace. It is environmentally benign ̶ non-toxic, non-flammable, odorless, tasteless, inert, and inexpensive. CO2 has been commonly used in decaffeination processes and more recently shown to be an effective supercritical solvent for extracting botanicals.
A major advantage of SFE with Co2 is that the extraction process can be finely tuned by a small reduction in temperature, or a slightly larger reduction in pressure, which will result in almost the entire solute precipitating out as the supercritical conditions are changed or made sub critical.
CO2 Extraction References