Differential Extraction

Extraction, in general, is the process of pulling a dissolved substance OUT of an aqueous solution by shaking that solution together with a suitable organic solvent that the substance is more soluble in. Differential extraction is exactly this technique put into practice using a separating funnel: the aqueous solution containing the organic substance is placed in the funnel together with a modest quantity of an immiscible organic solvent (ether or chloroform are named), and the two layers are shaken together gently. Because the dissolved organic substance is more soluble in the organic solvent than in water, it preferentially transfers ACROSS into that organic layer during the shaking. Once shaking is complete, the two layers are allowed to separate cleanly again (the organic solvent, being immiscible with water, forms its own distinct layer), and the solvent layer -- now carrying the extracted substance -- is s …