Influence of Adsorption Isotherms on Chromatogram Shapes

A chromatogram is influenced by several factors, such as the fluid dynamics inside the packed bed, mass transfer phenomena, and, most importantly, the equilibrium of the adsorption processes taking place. 

The adsorption equilibrium is typically described by isotherms, which give the correlations between the loadings of the solute on the adsorbent, q , as a function of the fluid phase concentrations, C , at a given temperature. Singlecomponent and competitive adsorption isotherms are discussed in more detail in Section 2.5. 

The elution profile of an ideal chromatogram depends only on the courses of the equilibrium functions characterizing the chromatographic system. To understand and predict real chromatograms additional mass transfer resistances and details regarding the fluid dynamics have to be taken into account. 

The retention times of specific concentrations in waves are then related to the local slopes of the specific adsorption isotherm as follows  

The second type of branches of overloaded ideal peaks is characterized by shock fronts having retention times described by Equation 2.18  

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