Thermo Scientific thermoscientific Vanquish UHPLC System, Руководство по эксплуатации

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8 • Troubleshooting
UHPLC System
Operating Manual Page 121
8.2.6 Retention Time Variation
Decreasing retention times
Possible Cause Remedial Action
Improper mobile phase
composition Check premixed mobile phase. Perform an OQ gradient accuracy test. A solvent
selector/proportioning valve may be defective. Contact Technical Support.
Increasing flow rate Check flow rate settings. Perform OQ flow precision test.
Increasing retention times
Possible Cause Remedial Action
Improper mobile phase
composition Check premixed mobile phase. Perform an OQ proportioning test. A solvent
selector/proportioning valve may be defective. Contact Technical Support.
Decreasing flow rate Check capillary connections for leaks. Check flow rate settings.
Piston seal leakage Check the pump for piston seal leakage (refer to Pump Operating Manual ).
Scattering retention times
Possible Cause Remedial Action
Imprecise solvent
proportioning • Perform an OQ eluent proportioning test.
• Clean the inlet check valve or outlet check valve, and replace the check valve if
necessary (refer to
Pump Operating Manual ).
• A solvent selector/proportioning valve may be defective. Contact Technical
Support.
Pressure fluctuations
from pump • Purge the pump.
• Check the compression values and take remedial action (refer to Pump Operating
Manual ).
• Check the pump for piston seal leakage (refer to Pump Operating Manual ).
• Check the solvent line filters for permeability. Replace the filter frits if necessary
(refer to
Pump Operating Manual ).
8.2.7 Baseline
High baseline drift
Possible Cause Remedial Action
System not sufficiently
equilibrated Flush the system until equilibration. Usually, a volume of 5–10 times the column
volume will be sufficient.
Unstable
environmental
conditions 1. Make sure that the temperature and the humidity are constant. You can
determine temperature fluctuations by recording the temperature channels.
2. Verify on the detector that the lamp house cover is properly installed and that the
front doors are closed. Avoid draft.
Flow cell contaminated Clean the flow cell. Replace the flow cell if necessary (refer to Detector Operating
Manual ).