5
Diagnostics
Determining the Delay Volume of the Pump
50
Accela Pump Hardware Manual
Thermo Scientific
4. From the Xcalibur data system, do the following:
a. In the Direct Control dialog box for the Accela Pump, select the
Take the pump
under control
check box (see
“Using Xcalibur to Start and Stop the Solvent Flow”
on
page 39
).
b. In the Flow box, type
200
to set the flow rate to 200
μ
L/min.
c.
In the Inlet box for the solvent reservoir bottle that contains 100% methanol,
type
100
.
d. Click
(Start).
e.
Click
Close
to exit the Direct Control dialog box.
f.
Go to
step 6
.
5. From the ChromQuest data system, download the method.
6. Collect one data file:
• For Xcalibur, create a one-line sequence containing the instrument method, and then
run the sequence.
• For ChromQuest, click the
Single Run
button. Enter the appropriate information in
the Single Run dialog box, and then start the run.
7. Calculate the gradient delay volume of the pump:
a. To determine the total gradient delay volume, multiply the gradient delay time by the
flow rate.
b. To determine the gradient delay volume of the pump, subtract the volume of the
tubing connecting the pump to the detector from the total gradient delay volume.
The results of your run should look like the chromatogram shown in
Figure 35
. The
gradient delay volume of the pump is calculated as follows:
Total gradient delay volume = T1
×
flow rate
Gradient delay volume of the pump = T1
×
flow rate - tubing volume
= (0.45 min
×
200
μ
L/min) – (0.32
μ
L/inch
× 25
inches)
= 82
μ
L
