Activity coefficients at infinite dilution (gamma(infinity)(i)) offer a valuable tool for solvent selection in extraction processes. In this study, the gamma(infinity)(i) values for solutes like alkanes, aromatics, and naphthenes in solvents, i.e., ionic liquids N-butyl-4-methylpyridinium tetrafluoroborate [BMPy][BF4], 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMPyr] [NTf2], and 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM] [BF4], were estimated using gas liquid chromatography at temperatures 313.1, 333.1, and 353.1 K. Partial molar excess enthalpies at infinite dilution (Delta H-1(E,infinity)) were evaluated from the gamma(infinity)(i) values. The selectivity for the toluene/n-heptane system was also calculated from the experimentally observed gamma(infinity)(i) and compared to the literature values for well-established industrial solvents