PL-GPC 220 User Manual 61
Troubleshooting and Diagnostics
5
General Troubleshooting Guide
Chromatography Problems
• RI baseline drift
• Allow sufficient time for the system to equilibrate at temperature (8 hrs
is usually enough).
• Ensure that the oven temperature remains stable (see “Oven
Temperature Control Problems” on page 60.
• Check that the pump flow rate / back pressure is constant.
• Check all plumbing connections between the Purge valve outlet and RI
Reference inlet.
• Check that the RI cell is not cracked.
• RI baseline noise
• Purge the Pump head to clear air from the Check Valves.
• Purge the RI Reference thoroughly to remove any air bubbles.
• Check for presence of pump noise. Clean or replace check valves if
necessary. The pump pressure is continually monitored when the
Logging is turned on and the pressure history can viewed in the log table
or plotted graphically –see the LOG MENU in the graphical user interface.
• Clean or replace inline filter element.
• Check that the degasser is operating correctly. The degasser pump motor
should cut in and out to maintain low chamber pressure. If it runs
continuously, there could be an air leak.
• Small or Non-Reproducible peaks
• Check that the vials are filled to shoulder.
• Inspect Valco valve seal for scoring and wear. May also see solvent drips
on the outside of vials.
• Check all autosampler tubing connections for leaks.
• Check that the autosampler needle is not blocked.
• Check that the autosampler syringe plunger seal is gas-tight.
• Check that the syringe Luer adaptor not leaking.
• Long retention times
• Check the pump flow rate.
• Check for a leak on the Purge valve.
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