What is liquid-liquid extraction? Also known as solvent extraction Separation of analytes from a liquid matrix by the use of another liquid based upon selective partitioning. Analytes are separated based on their different solubility in different liquids. Thus, the success of LLE depends upon the difference in solubility of an analyte in various solvents.How it works? It consists of two solvents that do not mix (diff solubility) First solvent contains the analyte of interest Second solvent acts to extract the analyte Since the two solvents do not mix, they can be separated in a separatory funnel providing a very quick and easy way to separate compounds.Solvent system As mentioned earlier, Solvent system must comprise of two immiscible solvents Usually one phase is a water or water-based (aqueous) solution and the other an immiscible organic solvent (often methylene chloride, diethyl ether, or ethyl acetate). Most common solvent pairs are water-hexane, water-dichloromethane, water-ether The analyte must be soluble in organic solvent but insoluble in waterDistribution When an analyte is shaken in a separatory funnel with two immiscible solvents, the analyte will distribute itself between the two solvents. Distribution coefficient A quantitative measure of how an organic compound (analyte) will distribute between aqueous and organic phases. K = distribution coefficient It is the ratio of the concentration of solute distributed in the two different solvent once the system reached equilibrium. Distribution coefficient, K is independent of the actual amounts of the two solvents mixed. Efficiency