Application of Solvatic Model for Prediction of Retention at Gradient Elution in Reversed-Phase Liquid Chromatography

There are several different approaches for LC method development; beside traditional, different software programs for method development and optimization are available. The solvatic retention model of reversed-phase LC was applied for prediction of retention in the gradient elution mode for aripiprazole and its related substances described in European Pharmacopoeia. As some of these compounds have very similar and others quite different chemical structure, their separation is challenge. Prediction was suitable on examined stationary phases (C18, C8 and phenyl-hexyl) with 0.1% phosphoric acid as aqueous mobile phase and acetonitrile or methanol as organic modifier. Predicted retention times take into account structural formulae of compounds and properties of stationary and mobile phases result in average difference of 14-17% compared to experimental ones on phenyl-hexyl stationary phase, where the highest matching was obtained. After utilisation of the retention models with data from one experimental run, the average difference decrease to maximal 7% and after contribution of data from two experimental runs, to maximal 2%. For majority of studied compounds difference between predicted and experimental values on all examined stationary phases is lower than 3%.