Figure 25 : The right graph helps to understand which separation mode in planar chromatography is the one you need for a special analytical problem. Examples: if no available phase system can bring the substances of your critical sample to a high enough chromatography position (because the k values remain high) you cannot succeed with the linear technique. Then you MUST select the circular mode of separation, as only this way even k = 500 data leave at least the start circle for quantitation.