Plants and Chromatography Separation of Photosynthetic Pigments by Paper Chromatography Paper Chromatography and Leaf Pigments Why do some pigments move further than the others? (What happens if the solvent is rubbing alchohol?) Solution Answer: The speed at which a particular pigment moves depends on its relative affinities for the two solvent phases-Mobile phase (solvent) and stationary phase (water) If the pigment has no affinity whatever for the water phase, it will travel at maximum speed. On the other hand, if the pigment has no affinity whatever for the non-polar phase, it will remain stuck at the origin of application..