Thermo Scientific thermoscientific Vanquish Pumps C, Operating Manual

Page: 236 / 296

10 • Modifying the Pump for Specific Applications
Page 236 Pumps C, Pumps F ( VC-Pxx, VF-Pxx)
Operating Manual
10.1 Gradient Delay Volume, Dwell Volume and Ripple
This section applies to binary pumps, quaternary pumps, and dual
pumps.
The gradient delay volume of an HPLC system is defined as the volume
of the entire flow path between the point where the gradient is formed
and the point where the mobile phase enters the column. Thus, the
gradient delay volume of an HPLC system is the volume that the pump
must deliver until a change in solvent composition reaches the column
inlet.
Figure 74: Gradient delay volume of an HPLC system
No. Description
1 Pump with
1a Point where the gradient is formed (purge unit)
Quaternary pump : The gradient is formed after the proportioning valve.
Dual pump : The gradient is formed after the proportioning valve (with each
of the two pumps).
Binary pump : The gradient is formed in the purge/sensor unit.
2 Autosampler
3 Column
4 Detector
5 Gradient delay volume of the system
Reducing the gradient delay volume allows changes in the solvent
composition to become effective on the column much earlier and thus,
having a faster effect on the elution of analytes.
The pump contributes to the system gradient delay volume by the dwell
volume (see
Pump-Specific Information ( } page 215) ). For the dwell
volume of the pump, see Performance Specifications ( } page 254) .