Resolution (chromatography)

This article is about the quantity used in chromatography. For other uses, see Resolution (disambiguation).

File:Chromatogram in English.svg

Example chromatogram showing signal as a function of retention time

In chromatography, resolution is a measure of the separation of two peaks of different retention time t in a chromatogram.

Expression

Chromatographic peak resolution is given by

$R_s=2\frac{t_{R2}-t_{R1}}{w_{b1}+w_{b2}}$

where t_R is the retention time and w_b is the peak width at baseline. The bigger the time-difference and/or the smaller the bandwidths, the better the resolution of the compounds. Here compound 1 elutes before compound 2.

If the peaks have the same width

$R_s=\frac{t_{R2}-t_{R1}}{w_b}$.

Plate number

File:Rt 5 15.png

Two resolved peaks in a chromatogram

The theoretical plate height is given by

$H=\frac{L}{N}$

where L is the column length and N the number of theoretical plates. The relation between plate number and peak width at the base is given by

$N=16\cdot {\left(\frac{t_R}{W_b}\right)}^2$.

See also

• Image resolution
• Resolution (mass spectrometry)
• Van Deemter equation

External links

• IUPAC Nomenclature for Chromatography