Plate Theory and Extensions - Effective Plate Number > Page 64



where (y) is the retention distance
and (x) is the peak width.

Now, the number of effective plates  (NE), by definition, is given by


where (yo) is the retention distance of an unretained solute (the position of the dead point).

Now from the plate theory,     


By dividing through by (vm ), and noting that  ,


Consequently,                         (57)

Equation (57) shows the relationship between efficiency and 'effective plates'. The number of 'effective plates' in a column is not an arbitrary measure, but is directly related to efficiency as derived from the plate theory. Equation (57)shows that, as (k') becomes large, (n) and (NE) converge to the same value.