Resolution (chromatography)

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

In chromatography, resolution is a measure of the separation of two peaks of different retention time t in a chromatogram.^[1][2][3][4]

Example chromatogram showing signal as a function of retention time

Expression

Chromatographic peak resolution is given by

${\displaystyle R_{s}=2{\cfrac {t_{R2}-t_{R1}}{w_{b1}+w_{b2}}}}$

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

${\displaystyle R_{s}={\cfrac {t_{R2}-t_{R1}}{w_{b}}}}$.

Plate number

Two resolved peaks in a chromatogram

The theoretical plate height is given by

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

where L is the column length and N the number of theoretical plates.^[5] The relation between plate number and peak width at the base is given by

${\displaystyle N=16\cdot \left({\frac {t_{R}}{W_{b}}}\right)^{2}\,}$.

See also

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

References

1. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Peak Resolution Rs in chromatography". doi:10.1351/goldbook.P04465
2. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Peak Resolution in gas chromatography". doi:10.1351/goldbook.R05317
3. Maryutina, Tatiana A.; Savonina, Elena Yu.; Fedotov, Petr S.; Smith, Roger M.; Siren, Heli; Hibbert, D. Brynn (2018). "Terminology of separation methods (IUPAC Recommendations 2017)". Pure and Applied Chemistry. 90 (1): 181–231. doi:10.1515/pac-2017-0111. ISSN 0033-4545.
4. Ettre, L. S. (1993). "Nomenclature for chromatography (IUPAC Recommendations 1993)". Pure and Applied Chemistry. 65 (4): 819–872. doi:10.1351/pac199365040819. ISSN 1365-3075.
5. IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "plate number, N". doi:10.1351/goldbook.P04694

External links

• IUPAC Nomenclature for Chromatography