Reversed-phase ion-pair systems for the prediction of n-octanol-water partition coefficients of basic compounds by high-performance liquid chromatography

• Published in: Journal of Chromatography A 1986-02, Vol.352, p.455-463
• Main Authors: Kraak, J.C., van Rooij, H.H., Thus, J.L.G.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Other chromatographic methods
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(01)83401-4

The correlation between the retention of basic solutes in a reversed-phase ion-pair system, in which sodium dodecylsulphate is the pairing-ion, and their n-octanol-water partition coefficients (log P) has been studied. The study comprises the influence on the correlation of the type hydrophobic matrix (phenyl- and octadecylsilica) and of the pH and salt concentration in the mobile phase. The influence of the ion-pairing additives on the prediction of log P of neutral compounds from their retention has also been studied. The results show that the correlation between log P and log k′ for basic compounds is significantly better on phenylsilica than on octadecylsilica. The error in the prediction of log P, ranging from 1 to 7, of basic compounds from their retentions in the ion-pair system on phenylsilica was found to be ± 0.1 log units at a 95% confidence limit. The correlation of log P values of neutral compounds with their k′ values in the ion-pair system is not significantly worse than that found with a normal reversed-phse system. Moreover, it seems that the slopes of the linear regression of log P and log k′ of neutral and basic compounds in the selected phases system are about equal. This permits the prediction of log P of neutral and basic compounds from their retention in the same phases system with an error in the prediction of ± 0.1 long units at a 95% confidence limit.