Gradient injection in preparative chromatography

This work is meant as a contribution to increase the understanding of preparative batch liquid chromatography. It investigates on the use of a different sample solvent for injection than for the elution – the gradient injection. The use of a stronger sample solvent for injection, as often used in pharmaceutical industry, has been given special consideration. For theoretical investigation of the gradient injection, solutions of the equilibrium theory have been applied and extended. This led to identification and derivation of general elution effects of such an injection method. The theoretical results have been verified in two experimental studies. Based on a experimental case study a rather simple and effective methodology has been suggested, suitable for process design and evaluation. It has been shown, that gradient injections have potential for process intensification. Suitable application areas and limits of the gradient injection have been identified.