Countercurrent chromatography: a worthy technique for the direct measurement of liquid-liquid partition coefficients

Countercurrent chromatography (CCC) is a liquid chromatography technique in which the stationary phase is also a liquid. The solute separation is based on partitioning between the two immiscible liquid phases: the mobile phase and the support-free liquid stationary phase. Octanol-water partition coefficients (Po/w) of 17 βblockers and 17 sulphonamides were determined by CCC. Some of the Po/w coefficients of the molecular forms disagreed with the theoretical and experimental values from literature. The Po/w coefficients of the ionic forms and the acidity constants were also calculated using a theoretical model. Relationships between biological properties and hydrophobicity are also discussed. On the other hand, the ionic liquid 1-butyl-3methylimidazolium hexafluorophosphate was used for the first time in CCC to estimate the distribution constants of different aromatic solutes, including bases, acids, and neutral compounds, between the ionic liquid-rich phase and the aqueous phase. The resulting distribution constants were compared with the corresponding literature octanol–water partition coefficients.