Determination of gas-liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary GC columns

RONCO, N.; MENESTRINA, F.; ROMERO, L. M.; CASTELLS, C. B.

JOURNAL OF CHROMATOGRAPHY - A

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017

0021-9673

Inthis paper, we report gas-liquid partition constants for thirty-fivevolatile organic solutes in the room temperature ionic liquidtrihexyl(tetradecyl)phosphonium bromide measured by gas-liquidchromatography using capillary columns. The relative contribution ofgas-liquid partition and interfacial adsorption to retention wasevaluated through the use of columns with different phase ratio. Four capillary columns with exactly known phase ratioswere constructed and employed to measure the solute retention factorsat four temperatures between 313.15 and 343.15 K. The partitioncoefficients were calculated from the slopes of the linear regressionbetween solute retention factors and the reciprocal of phase ratio ata given temperature according to the gas-liquid chromatographictheory. Gas-liquid interfacial adsorption was detected for a fewsolutes and it has been considered for the calculations of partitioncoefficient. Reliable solute´s infinite dilution activitycoefficients can be obtained when retention data are determined by aunique partitioning mechanism. The partial molar excess enthalpies atinfinite dilution have been estimated from the dependence ofexperimental values of solute activity coefficients with the columntemperature. A thorough discussion of the uncertainties of theexperimental measurements and the main advantages of the use ofcapillary columns to acquire the aforementioned relevantthermodynamic information was performed.