Molecular mechanism of retention in reversed-phase high-performance liquidchromatography and classification of modern stationary phases by using quantitative structure-retention relationships

Quantitative structure-retention relationships (QSRRs) were derived for log arithms of retention factors normalised to a hypothetical zero percent orga nic modifier eluent, log k(w), determined on 18 reversed-phase high-perform ance liquid chromatography (RP-HPLC) columns for 25 carefully designed, str ucturally diverse test analytes, The study was aimed at elucidating molecul ar mechanism of retention and at finding an objective manner of quantitativ e comparison of retention properties acid classification of modern stationa ry phases for RP-HPLC, Three QSRR approaches were employed: (i) relating lo g k(w) to logarithms of octanol-water partition coefficient (log P); (ii) d escribing log k(w) in terms of linear solvation-energy relationship-based p arameters of Abraham; (iii) regressing log k(w) against simple structural d escriptors acquired by calculation chemistry. All the approaches produced s tatistically significant and physically interpretable QSRRs. By means of QS RRs the stationary phase materials were classified according to the prevail ing intermolecular interactions in the separation process. Hydrophobic prop erties of the columns tested were parametrized, Abilities of individual pha ses to provide contributions to the overall retention due to non-polar Lond on-type intermolecular interactions were quantified. Measures of hydrogen-b ond donor activity and dipolarity of stationary phases are proposed along w ith two other phase polarity parameters. The parameters proposed quantitati vely characterize the RP-HPLC stationary phases and provide a rational expl anation for the differences in retention patterns of individual columns obs erved when applying the conventional empirical testing methods. (C) 1999 El sevier Science BN. All rights reserved.