Adsorption equilibrium for Z-ligustilide on C18-bonded silica from supercritical carbon dioxide

In the adsorption process of Z-ligustilide from supercritical carbon dioxide on C18-bonded silica, the density of mobile phase and the temperature are two important factors that influence the adsorption capacity. The adsorption capacity of Z-ligustilide decreased with the increasing density of the SC-CO2 mobile phase as well as the increasing temperature, which is conformed to the basic principle of thermodynamics. The adsorption equilibrium data were fitted by Langmuir and Freundlich isotherm models, and the Langmuir isotherm model performed better for describing the whole adsorption process on the column. The obtained model can be applied for the engineering design and the optimization of separation of Z-ligustilide with pre-SFC.185