Equivalence between the equilibrium dispersive and the transport model in describing band broadening in analytical gradient liquid chromatography

• The ED and the TR model in analytical gradient liquid chromatography are compared.
• The ED and the TR model may be equivalent when the column efficiency is not small.
• The plate height equation derived from the TR model is also suited for the ED model.

It is shown that the transport (TR) model may be equivalent to the equilibrium dispersive (ED) model in analytical gradient liquid chromatography when the column efficiency is not small. This result is obtained by assuming that the gradient profile is not distorted, the injection is an impulse, and the apparent axial dispersion coefficient (Da) of the ED model or the lumped kinetic coefficient (kfL) of the TR model varies with mobile phase composition. According to this equivalence, the plate height equation derived from the TR model in our previous work (Eq. (91) in Hao et al., 2013) is also suited for the ED model. This conclusion is confirmed by comparing the equation with the results obtained by Gritti and Guiochon from the ED model (Gritti and Guiochon, 2012).