•Shortcomings of Plate Theory
•Assumes K is independent of concentration
•Assumes equilibration is rapid relative to velocity of mobile phase – not true, in reality solute may pass a plate without entering
•Assumes no longitudinal diffusion (= non ideal effect that causes band broadening)
•Does not address several factors caused by mobile phase velocity (fast or slow) Rate Theory
•Assumes discrete units or plates for equilibrium rather than a semi continuous process through the column