This Information Applies to: Agilent 1100, 1200, and 1260 LC quaternary pumps.
Issue
Pressure has been fluctuating or causing ripple. It may cause a noisy baseline and retention shifts, therefore, the quality of chromatograms has worsened.
Pressure fluctuations can occur when the pump is not delivering a flow correctly and it affects the separation during analysis.
Resolution
Air trapped in the pump head
Purge the pump, and flush the system with mobile phase or IPA, first without a column. Then condition the system with mobile phase with the column installed.
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Caution: Make sure that the compressibility settings of the pump in the method are compatible with the solvents used.
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To ensure efficient air bubble removal from the pump, use the reasonable method conditions compatible with the column, for example a flow of 1.5 mL/min, with composition setting of A: 50 % B: 50 % and backpressure of >200 bar. Purge for at least 30 min or until the pressure ripple is fixed.
Capillaries
A buildup of particulates can occur and disturb the laminar flow. If the sample and mobile phase are subject to those particulates, make sure that the inlet filters are installed and the sample is filtered before injection into the system.
Flushing the system with a union instead of the column will help get rid of the particles.
Degasser
Check for bubbles in outlet lines.
The degasser may not be working correctly. Bypass it to check if it is the case.
Sonicate the mobile phases for 20 minutes and connect the solvent lines directly to the pump. Run a sample and see if there is any improvement on the analysis or pressure ripple.
If the previous procedure improved the pressure issue, it might be a problem with the degasser. Connect the degasser again and run more samples to confirm your findings. In case you suspect of the degasser, contact your local Agilent Support Representative.
Failing valves
If there is no improvement with the previous procedures, check the outlet ball valve and the inlet valve. They may be leaking or not working properly.
They can also be diagnosed by ripples or a dented pressure profile with a 5 to 6% ripple on the pressure plot.
Sonicate the inlet and outlet valves according to the article How to Sonicate the Inlet and Outlet Valves of Agilent 1100, 1200 and 1260 Series Pump Head.
If the sonication is not bringing any improvement, replace the outlet ball valve, then passive or active inlet valve cartridge.
Leaking pump seals
If a seal wash is installed, turn it off and disconnect the wash tubing.
The leak can be small one, set the flow at high flow and see if there is any solvent coming out of the pump head.
Check if there is any leak occurring on the pump head. If so, replace the piston seals.
Failing Multichannel Gradient Valve (MCGV)
See the article Troubleshooting MCGV Cross Port Leaks in Quaternary Pumps
If the cross port leak MCGV is suspected, contact your local Agilent Support Representative for further support.
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Learn how to effectively troubleshoot your Agilent quaternary pump:
HPLC-1260-1273e - Agilent 1260 Infinity LC with OpenLab CDS High Pressure Errors HPLC-1260-1271e - HPLC High Pressure Errors e-learning courses available from Agilent education |
