A REVIEW OF NATURAL PRODUCTS FROM PLANTS USING CARBON DIOXIDE SUPERCRITICAL FLUID EXTRACTION
Supercritical fluid extraction (SFE) is the most effective and efficient way to extract valuable constituents from plants. SFE is the process of separating one component (the extractant) from another (the matrix) using supercritical fluids that is CO2 as the extracting solvent. It is a well-established process for recovery of different organics, mainly nonpolar substances from various solid matrixes. CO2 is the most common used extraction solvents for botanicals. Extraction conditions for supercritical CO2 are above its critical temperature of 31 °C and critical pressure of 74 bar. Supercritical fluids are highly compressed gases, which have combined properties of gases and liquids in an intriguing manner. Supercritical fluids can lead to reactions which are difficult or even impossible to achieve in conventional solvents. In addition, supercritical fluid can be separated from analytes by simply releasing pressure, leaving almost no trace and yields a pure residue. The use of supercritical carbon dioxide is a simple, inexpensive, fast, effective and virtually solvent–free sample pre-treatment technique. In this research, a complete study on supercritical carbon dioxide extraction of natural products from plants is carried out to examine the principal of this method, the bioactive compounds that can be extracted and also the effect of process variables on extraction yield. Finally, SFE also has been compared with other conventional and non-conventional extraction methods in terms of selectivity, rapidity, cleanliness and possibility of manipulating the composition of the extract.