Preparative chromatography is the most widely used purification method in the biotechnology and pharmaceutical industry. Here, one theoretical and one practical problem of preparative chromatography are investigated. The theoretical problem deals with the effect of experimental error on the precision of adsorption isotherm parameters estimated by numerical method. Numerical method has becoming popular in recent years as a quick alternative to the classical dynamic methods for adsorption isotherm determination. However, the fundamental problem of the numerical back-propagation of error has not been addressed in the literature. In this study, the variance in the final estimated parameters as a function of experimental error is quantified. The results indicate that it is theoretically possible to obtain sufficiently accurate parameters from multiple experimental replicates. The number of experimental replicates required to achieve isotherm parameters with less than 5% error is calculated explicitly for a variety of data sets. By using computer simulated experimental data, the effect of error in effluent concentrations and error in retention times are addressed separately. The practical problem is about the optimization of preparative purification of chlorophyll a by countercurrent chromatography (CCC). CCC offers several advantages over high performance liquid chromatography (HPLC) and is a fundamentally preparative separation tool. The process reported here is capable of producing several hundreds of milligrams of chlorophyll [alpha] with a high purity in a short time. The CCC separation is optimized for good production rate and recovery yield with respect to loading conditions.