Figure 31 : The classical theory in HPLC used for many years the partition coefficient K to make specific separations understandable. The weak point in this way to treat liquid chromatography is the fact, that (column) separation is possible ONLY under dynamic conditions. Something must move. We have speed and time. Thus the residence time in the mobile phase versus the residence time in the stationary phase counts. We could drastically change the polarity of a separation system by influencing the residence times - example: changing the flow speed or the temperature in DIFFERING parts of the stationary phase. NOTE: the changes were drastically - by third power of the changes.These modes are not yet (up to 2009) used in PLC. They are promising.