The design of safe and environmentally benign separation processes has an increasingly important role in the chemical industry. Room-temperature ionic liquids are promising solvents because they have no measurable vapor pressure, so atmospheric contamination is avoided. In this work, new liquid-liquid equilibrium data were determined to prove that 1-butyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid can be an excellent extractant agent of ethanol from its mixtures with tert-amyl ethyl ether, thus allowing ether purification. The experimental technique is based on direct analysis of phases at equilibrium using H-1 NMR, which allows quantitative analysis of the three chemicals and thus reduces the experimental error. The phase equilibrium data were satisfactorily correlated using the nonrandom two-liquid equation.