Model-independent aspects of perturbation chromatography theory

Abstract

Suitably defined mean times for the response of a chromatographic column to step and small-pulse perturbations are shown to be independent of the nature of the mass transfer processes within the column.The mean times depend solely on equilibrium properties and may be determined from measurements of the response. For a step response the mean time for a particular species is equal to the ratio of the change in the equilibrium holdup in the column of that species to the change in the rate at which it is transmitted through the column. For a pulse response the mean time is the derivative of the holdup with respect to the transmission rate. Retention volumes are also related to equilibrium and not rate properties when defined as the volume of mobile phase that flows into the column up to the mean time.