The paper, dipped in the green solution is covered with layers of different pigments
name: Pigments contained in green leaves are well separated by paper chromatography
There is a stationary (in this case it's paper) and movable (isopropanol which rises on the paper) phases in any kind of chromatography. The separation of various substances is due to the different affinity for the mobile and stationary phases.During the process of chromatography, equilibrium is established between the free (dissolved in isopropanol) and related with paper molecules, which determines the average speed for each of the substances to be separated.
So, if at any given time 50% of the molecules are associated with the paper and, accordingly, do not move with the flow, the average speed of the substance is equal to half the isopropanol velocity. Chromatography can be conveniently described by a holding factor. This is the ratio of the distance traveled by a substance to the distance traveled by the solvent.
The leaves contain a variety of pigments that can be separated by this method. Therefore, the leaves turn yellow in fall.