Chromatography in silica, quantitative analysis of retention mechanisms of benzoic acid derivatives

A quantitative analysis of the retention of benzoic acid derivatives in reversed-phase liquid chromatography was achieved using a molecular mechanics calculation in the CAChe program. Interaction energy values were calculated for both molecular and ionic forms. The predicted retention factors of partially ionized acids obtained using a combination of dissociation constants well correlated with the values measured by reversed-phase liquid chromatography with pH-controlled eluents. The molecular interaction energy value was calculated by subtracting the energy value of the complex from the sum of energy values of a model-phase and an analyte.