Extraction with organic solvents at ambient pressure Extraction with organic solvents is principally used in the perfumery and cosmetic industries. Methods involving solvent extraction are particularly difficult to control.
Many plant materials require some degree of comminution before treatment with a solvent.
This grinding is often accompanied by heat and may lead to volatile losses and chemical change. Green plants have a very high quantity of water and it is difficult to obtain an appropriate solvent to extract the components from the aqueous cells. Even when a very high-speed blending is used, the partition equilibrium may be slow and repeated extractions necessary to obtain a satisfactory yield. Extraction may be improved by using dried material. But when drying is used some decomposition can occur, and aromatic materials from natural sources differ widely in their physical and chemical properties, particularly in their volatility and solubility, so the choice of the solvent may determine the success of the extraction.