Plate theory concept was introduced to explain efficiency of columns. The concept ASSUMES that a state of instantaneous equilibrium EXISTS between the CONCENTRATION of solute in stationary phase and the mobile phase and further the column is imagined to be divided into a number of theoretical PLATES. Any analyte spends a finite time in each plate and this is the equilibrium time. Smaller the plate height the greater is the number of plates in a given LENGTH (HETP) and better is the column resolution.

Plate theory concept was introduced to explain efficiency of columns. The concept assumes that a state of instantaneous equilibrium exists between the concentration of solute in stationary phase and the mobile phase and further the column is imagined to be divided into a number of theoretical plates. Any analyte spends a finite time in each plate and this is the equilibrium time. Smaller the plate height the greater is the number of plates in a given length (HETP) and better is the column resolution.