Gas liquid chromatography was used to determine solute retention data for 33 volatile organic solvents: alkenes, alkanes, alkynes ketones, alcohols, aromatic hydrocarbons, tetrahydrofuran, acetonitrile, thiophene, and water in the new ionic liquid (IL) 2,3-dihydroxypropyl-N-methyl-2-oxopyrrolidinium chloride [(OH)(2)C(3)MPyr] [Cl]. This work was conducted in order to evaluate the IL for use in separation processes, and the evaluation was based on the experimental activity coefficients at infinite dilution. y(13)(infinity) was obtained at four different temperatures (313.15-343.15) K. The molecular interaction occurring within the solutes and IL was discussed. The types of interactions were further explained by calculating the following physicochemical properties at infinite dilution partial molar excess enthalpies, Delta H-1(E,infinity), Gibbs free energy, Delta G(1)(E,infinity) and the entropy term, T-ref Delta S-1(E,infinity). This work provides insight about the nature of 2,3-dihydroxypropyl-N-methyl-2-oxopyrrolidinium chloride IL, the effect of the structure on thermodynamic properties, the influence of polar functional groups, and choosing a suitable solvent for distinct separation problems. Separation parameters (capacity and selectivity) for some of the petrochemical extraction problems (heptane/thiophene, heptane/benzene, heptane/1-heptyne) were calculated from gamma(infinity)(13) data and compared to the literature values with other ILs. The prescreen of separation agents can be determined from the activity coefficients at infinite dilution data.