Gradient Curves

The Dionex UltiMate 3000, P680, GP40, GP50, and GS50 pumps let you specify linear or non-linear %-Gradient profiles (gradient curves). Eluent Generators can also deliver non-linear %-gradient profiles. For the mathematical description of the curve types, refer to Gradient Curves Equations.

Curve 5 (the default) is linear. Changes in composition of the delivered solvent over time are constant.

Curves 1 - 4 are convex upward. Convex curves cause rapid changes in solvent composition at the beginning of the gradient and slower changes at the end. Slope changes over time become extreme as curves go from 4 (least convex) to 1 (most convex).

Curves 6 - 9 are concave upward. Concave curves cause slower changes in solvent composition at the beginning of the gradient and rapid changes at the end. Slope changes over time become extreme as curves go from 6 (least concave) to 9 (most concave).

In addition, you can define step gradients directly in the gradient table (for example, step A and B). As a result, more than 11 different options to change the gradient are available.

 Note:  

The statements regarding curves 1 to 11 also apply to some third-party devices. However, the curvature may deviate.

For information on how to create user-defined flow and gradient profiles using the PGM Wizard, refer to chapter   Flow/Gradient Options/Multi-Step Gradient.