Delay Time
The time required for a substance to travel from one location in the chromatography system to another is referred to as the delay time.
In a gradient system, the delay time is the time required for a change in the gradient composition to migrate from where the gradient is formed to the head of the column. The gradient delay time is proportional to the volume between the point at which the gradient is formed and the head of the column, and is inversely proportional to the flow rate. As an example, the delay time in a Dionex RFIC (Reagent-Free Ion Chromatography) system using a gradient pump is typically about 0.8 minute.
Sometimes, the delay time is used to refer to the time related to the delay volume between the following system components:
The separator column and the detector cell
The first detector cell and a second (or third) detector cell
The detector cell and the switching valve (or the tube, depending on the device type)
On the General tab page of the QNT Editor (see The QNT Editor 
The General Tab Page), enter the Delay Time needed by a substance to travel from the detector cell of the first detector to the detector cell of a second detector. If a third detector is installed, the delay time is the time between the detector cell of the first detector and the detector cell of a third detector. (For information about the editor, see Data Representation and Reprocessing The QNT Editor.)
On the Fraction Collection Options page of the Program Wizard (see Control The Program Wizard), enter the delay time between the detector and the Fraction Collector. The wizard displays this page only if you installed the Fraction Collection driver in the Server Configuration program. If you use several additional detectors, enter the delay time(s) between the detectors on the Fraction Collection - Channel Selection Options page.
Tip:
Enter a fixed delay time only if the flow is constant. Changing the flow rate also changes the actual delay time between two detectors or between the detector and the fraction collector.