Flow Gradient

Changes to the Flow rate in a chromatogram are referred to as a flow gradient. This type of Gradient is quite unusual in liquid chromatography. However, compared to the ordinary %-Gradient, the flow gradient has the advantage that the solvent composition does not change in the column. Thus, you do not need to condition the column before starting the next analysis.

The gradient can be generated manually or program-controlled. You can change the flow either continually (Ramps) or immediately (Step Gradient).

 Note:

Pumps that are serially controlled deliver a specific flow rate by commands. It is not possible to enter an unlimited number of these commands in very short intervals. Therefore, a flow gradient generated in this way has very small steps, which, however, are almost immeasurable. Pumps with voltage, frequency, or pulse width control can continually change the delivery rate so that there are virtually no steps.