Question

To obtain a resolution of 1.50, how many theoretical plates must a packed column have for two peaks which elute at 5.42 and 5.63 minutes, where t_m = 1.00 min? With a resolution of 1.50, are these peaks considered to be resolved?

Answer 1

Now the equation that relates resolution (Rs) of a column with therotical plates (N) is

Rs = [[(t_R)_B - (t_R)_A ] X square root of(N)] / [(t_R)_B X 4]

where (t_R)_B = retention time of peak B here 5.63 min

( t_R )_A = retention time of peak A here 5.42 min

R_s = resolution = 1.5

N =theoritical plates = ?

putting these values in above equation

1.5 = [(5.63 - 5.42) X square root of(N)] / (5.63 X 4)

N = 23875.02

if R_s = 1.0 it is considered to be adequate most of the separations so here at resolution 1.5 these peaks considered to be well resolved