Purnell equation
# Purnell equation

The Purnell equation is an equation used in analytical chemistry to calculate the resolution $R_s$ between two peaks in a chromatogram.

    $R_{s}={\frac {\sqrt {N_{2}}}{4}}\left({\frac {\alpha -1}{\alpha }}\right)\left({\frac {k'_{2}}{1+k'_{2}}}\right)$

where

       $R_s$ is the resolution between the two peaks
       $N_2$ is the plate number of the second peak
       α is the separation factor between the two peaks
       k $'_2$ is the retention factor of the second peak.

The higher the resolution, the better the separation.

