Gas-liquid chromatography (GLC) was used to examine the types of interactions among the volatile organic solvents (VOS) and (trihexyltetradecylphosphonium-bis-(2,4,4-trimethylpentyl)-phosphinate, [P-14,P- 6,P- 6,P- 6] [(C8H17)(2) PO2)], a phosphonium based ionic liquid. Activity coefficients at infinite dilution (gamma(infinity)(13)) was determined for 26 solutes, including alkanes, alkenes, cycloalkanes, cycloalkenes, ketones, alcohols, aromatic hydrocarbons, tetrahydrofuran, acetonitrile, thiophene and water at different temperatures i.e. 313.15, 323.15, 333.15 and 343.15 K. The gamma(infinity)(13) data was obtained with the use of packed column with a mass fraction loading of the ionic liquid from 0.28 to 0.35 in the stationary phase. The temperature dependent data of gamma(infinity)(13)was used to compute the partial molar excess enthalpies Delta H-1(E,infinity), entropies Delta S-1(E,infinity) and Gibbs energies Delta G(1)(E,infinity) at infinite dilution for the solutes. The capacities (k(j)(infinity)) and selectivities (S-ij(infinity)), at infinite dilution for the selected extraction problems were also computed from gamma(infinity)(13) and compared with values from literature. Examination of activity coefficients at infinite dilution gives a better understanding regarding the interactions among the ionic liquid and investigated compounds. (C) 2019 Elsevier Ltd.