Excessive Duration Or Higher Pressure For The Column Equilibration And Sample Loading Steps - Thermo Scientific EASY-nLC 1200 Troubleshooting And Maintenance Manual

Excessive Duration or Higher Pressure for the Column Equilibration and Sample
Loading Steps
Table 15. Common causes of a longer than expected column equilibration time or sample loading time
Symptom
When the method specifies a set
flow rate for the column
equilibration, sample loading, or
both of these steps, the pressure is
higher than usual.
When the method specifies a
maximum pressure for one or both
of these steps, the duration of these
steps is longer.
Thermo Scientific
Table 15 lists possible causes for the following:
• When the column equilibration and sample loading steps are controlled by a specified
pressure, the duration of these steps is longer than expected.
• When these steps are controlled by a specified flow, the pressure is higher than expected
during the column equilibration step, the sample loading step, or both steps.
During the sample loading and column equilibration steps, pump A delivers the user-specified
volume of solvent A to the system at the user-specified flow rate or maximum pressure or the
maximum system pressure. When the columns or the Column Out line is clogged, the system
must lower the flow rate to maintain the pressure at the maximum pressure specified in the
method. The lower flow rate increases the column equilibration time, the sample loading
time, or both.
Possible cause
Clogged column
Clogged system
Figure 118 and Figure 119
run and a run with a partially clogged column, respectively. The flow rate for a run with a
clogged column is lower than the flow rate for a normal run. The lower flow rate increases the
duration of the column equilibration and sample loading steps.
Note The specifications for the precolumns used to acquire the data in
Figure 118 and Figure 119
• 2 cm length
• 100 µm ID
• 5 µm particle size
• C18
Action
Run the Back Pressure script for pump A
(see
If the test passes, one of the columns is
probably clogged and must be replaced.
Run the Back Pressure script for pump A.
If the test fails, go to
System Blockage"
show the flow rate and pressure traces for pump A for a normal
are as follows:
EASY-nLC 1200 Troubleshooting & Maintenance Guide
"Back Pressure" on page
"Troubleshooting a
on page 208.
7
Troubleshooting
Troubleshooting Tips
47).
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