Quantitative structure–retention relationships of phenolic compounds without Hammett’s equations

Retention times of phenolic compounds in a given pH eluent in reversed-phase liquid chromatography were predicted from dissociation constants derived from atomic partial charges and log P-values calculated by a computational chemical method. The precision of the calculation of atomic partial charges by AM1 and PM3 methods of MOPAC™ was evaluated. The atomic partial charges obtained by AM1 were the more acceptable. The atomic partial charges obtained from the hydrogen of the hydroxyl group included an ortho-effect, therefore an ortho-effect was added to the predicted pKa values. The precision of predicted retention factors obtained using predicted pKa values was similar to that using reference pKa values.