Solvent Extraction Method

Solvent Extraction Method

This method is best suited for plant materials that yield low amounts of essential oil, that are largely resinous, or that are delicate aromatics unable to withstand the pressure and distress of steam distillation. This method also produces a finer fragrance than any type of distillation method.

Solvent Extraction is a most commonly process which involves extracting oil from oil-bearing materials by treating it with a low boiler solvent as opposed to extracting the oils by mechanical pressing methods (such as expellers, hydraulic presses, etc.). Direct extraction of rice bran, sal seed and soybean is also used.

The properties of a good solvent extraction are very much like those of a recrystallization solvent (favorable temperature coefficient; BP low enough to be easily evaporated and less than MP of solute; does not react with the solute). That means that other species are insoluble in the extraction solvent.

Commonly used solvents like ethyl acetate (8.1 %), diethyl ether (6.9 %), dichloromethane (1.3 %) and chloroform (0.8 %) dissolved up to 10 % in water. Water also dissolves in organic solvents: ethyl acetate (3 %), diethyl ether (1.4 %), dichloromethane (0.25 %) and chloroform (0.056 %).

Water is very capable of dissolving a variety of different substances, it is such a good solvent. And, water is called the "universal solvent" because it dissolves more substances than any other liquid.

Extraction with different solvents like acetone, chloroform, distilled water, ethyl acetate, hexane and methanol were done using soxhlet apparatus. Briefly, for every 200 mL of the each solvent, 25 g of the crushed plant leaves powder was used for soxhlet extraction.