Purnell equation
The Purnell equation is an equation used in analytical chemistry to calculate the resolution Rs between two peaks in a chromatogram. R s = N 2 4 ( α − 1 α ) ( k 2 ′ 1 + k 2 ′ ) {\displaystyle R_{s}={\frac {\sqrt {N_{2}}}{4}}\left({\frac {\alpha -1}{\alpha }}\right)\left({\frac {k'_{2}}{1+k'_{2}}}\right)} where Rs is the resolution between the two peaks N2 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.