The Purnell equation is an
equation
In mathematics, an equation is a formula that expresses the equality of two expressions, by connecting them with the equals sign . The word ''equation'' and its cognates in other languages may have subtly different meanings; for example, in ...
used in
analytical chemistry
Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separati ...
to calculate the resolution ''R''
s between two peaks in a
chromatogram
In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system (a ...
.
:
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 In chromatography, the retardation factor (''R'') is the fraction of an analyte in the mobile phase of a chromatographic system. In planar chromatography in particular, the retardation factor ''R''F is defined as the ratio of the distance traveled b ...
of the second peak.
The higher the resolution, the better the separation.
References
Chromatography
Equations
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