Liquid Chromatography with Linear Adsorption Equilibrium and Plate Model

Liquid chromatography is a common technique in analytical chemistry used to identify and quantify chemical species in a mixture. The mixture is injected at the inlet of a chromatographic column and a liquid mobile phase (the solvent) allows their elution. The liquid chromatography technique is based on the difference in adsorption of the chemicals on a solid stationary phase or adsorbent. Hence, different chemical species will elute at different retention times.

In this Demonstration, two components (A and B) are separated by liquid chromatography using the stagewise model. This model considers the chromatographic column to be a series of 50 well-mixed stirred tanks or 50 perfect equilibrium stages. Linear adsorption isotherms with equilibrium constants are assumed for this stagewise model. The two peaks at the exit of the column are plotted. These peaks are symmetric because of the linear equilibrium hypothesis. The order of elution of the two components depends on the relative values of their equilibrium constants, which can be chosen by the user. Due to dispersion, peaks get broader and smaller for larger elution times.