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Gradient

Seen on method statements.

Definition

The programmed change in mobile-phase composition across a run. A gradient lets one method separate components with very different retention in a reasonable time, and it is part of the method identity: the same column with a different gradient is a different method and can give a different purity figure.

Related terms

Reversed-phase chromatography
A separation in which the stationary phase is non-polar and the mobile phase is polar, so components are retained according to how hydrophobic they are and are released as the solvent strength increases.
Resolution
A numerical measure of how completely two adjacent peaks are separated, combining their spacing and their widths.

About chromatography

Separation, detection, and the figures that come out of a chromatographic run.

Retention timeArea purityIntegrationBaselineCo-elutionTailing factorTheoretical platesDetection wavelengthChromophoreIon pairingOrthogonal methodSignal-to-noise ratio

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