Chasing the elusive hold-up time from an LFER approach.

A homologous series approach derived from the Abraham's solvation model was developed for the determination of hold-up times. Firstly, it was tested from reversed-phase liquid chromatography data obtained in the literature involving several series of homologues, followed by its application in a polymeric zwitterionic HILIC column using two different homologous series (n-alkyl benzenes and n-alkyl phenones). Acetonitrile and methanol were selected as organic modifiers in a composition range between 80% and 100% in volume. Results obtained for both series were consistent, and hold-up times were found to be strongly dependent on the water content and the organic modifier nature of the mobile phase.