Example:
The separation shown below was obtained with a 3 m column. What is the minimum column length necessary to obtain a resolution of 1.5?
Figure: Calculation of required plates
Norig =16(x/y)2 =16(17/1)2 =4624 plates
α = 17-1/14-1 =1.231; k2 =17-1/1=16
Nreq= 16 Rs2 (α/α - 1)2( k2+ 1/k2)2
=16(1.5)2(1.231/1.231-1)2(16+1/16)2
=36(28.4)(1.13)= 1155 plates
Lreqd =Lorig× Nreq/Norig
=3× 1155/4624 =0.75 m
Thus, a much shorter column will provide a satisfactory separation. Since the separation is complete on the 3 m column then higher flow rates can be used to reduce the analysis time.