Introductory experiments of chromatography are often conducted by separating colored samples such as inks, dyes, and plant extract using filter paper, chalk or thin layer chromatography plates with various solvent systems. Many simple experiment have been reported. The relationship between normal chromatography and reversed-phase chromatography is however seldom illustrated with experiments. Where such experiments exist HPLC although TLC systems and paper chromatography have also been reported.
As is well known green leaves contain the colored compounds chlorophyll a and b and the main carotenoids such as carotene and xanthophylls. These compounds are ideal for demonstrating simple chromatographic principles as they are easily distinguishable from each other by their retention and their colors. The appearance of pheophytn as a singular grayish spot between the green chlorophylls and the yellow carotenoids provides a particularly valuable reference when the sequence of the migration is to be compared between different separation systems. Previously we have reported how normal and reversed-phase chromatography can be illustrated using paper chromatography of extracts of dandelion leaves which are rich in pheophytin. In normal-phase chromatography the stationary phase is relatively hydrophilic whereas the mobile phase is more hydrophobic. In reversed-phase chromatography the characteristics of both stationary and mobile phase are the opposite resulting in a reversed elution order to that obtained when using normal-phase chomatography.