The effect of interactions between 64 organic solvents and water on the interfacial and bulk properties at infinite dilution of two ionic liquids (ILs) namely N-triethyl-N-octylammonium bis(fluorosulfonyl)imide, [N-2,N-2,N-2,N-8][FSI] and 1-butyl-3-methylpyrrolidynium bis(fluorosulfonyl)imide, [BMPyr][FSI] were determined via measurement of activity coefficients gamma(infinity)(13) at infinite dilution using the gas-liquid chromatography technique. Measurements were undertaken at six temperatures, in 10 K intervals, in the range of (318.15 to 368.15) K. The solutes studied included both non-polar and polar compounds, as alkanes, alkenes, and alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, pyridine, thiophene, esters, acetonitrile and 1-nitropropane. The gas-liquid partition coefficients, K-L at infinite dilution, and the fundamental thermodynamic functions, partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements. The values of selectivity and capacity for four important in petrochemical technology separations, viz. hexane/hex-1-ene, hexane/benzene, cyclohexane/cyclohexene, and cyclohexane/benzene were calculated from gamma(infinity)(13) values and compared to literature data for ammonium ILs with different cations and anions and for ILs with [BMPyr](-) cation and different anions. The results from the study indicate that [N-2,N-2,N-2,N-8][FSI] reveals not satisfied selectivity values in comparison with [BMPyr][FSI] and literature values for all four of the separation cases studied. (C) 2018 Elsevier Ltd.