The Purnell equation is an equation used in analytical chemistry to calculate the resolution R<sub>s</sub> between two peaks in a chromatogram.
where
:R<sub>s</sub> is the resolution between the two peaks
:N<sub>2</sub> is the plate number of the second peak
:ñ is the separation factor between the two peaks
:k '<sub>2</sub> is the retention factor of the second peak.
The higher the resolution, the better the separation.
References