ABSTRACT
This chapter discusses the methods available for the evaluation of the basic parameters encountered during percolation through porous media and modelling of chromatographic interactions. For internal diameters up to 20 mm, the majority of lab-scale preparative supercritical fluid chromatography (SFC) experiments have been carried out successfully on prepacked columns which can also be used in liquid chromatography. The eluent should also be chosen with care in order to prevent solute precipitation. Hydrodynamic peak-broadening can be expressed through an equation describing an increase of HETP with the packing length, especially if the velocity distribution on a bed section is not perfectly flat. Retention mechanisms were described by several authors who tried to correlate retention factors and thermodynamical parameters. Mass balance equations are used as models for the separation of citral and limonene with the Peng Robinson equation of state modelling gas-liquid equilibrium. Frontal chromatography is in many cases very similar to adsorption/desorption processes defined by chemical engineers.
