Decreasing pressure or low pressure

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Probable cause		Suggested actions
1	NOTE: Air bubbles can form in the system overnight, causing fluctuating pressure. NOTE: Due to its miscibility with water and most organic solvents, isopropanol is often the choice when removing air bubbles from an HPLC system.	Ensure that the system is properly purged with the mobile phase. Degas mobile phases. Purge the pump and system with a viscous mobile phase to remove any air bubbles.
2	Sticking check valve	Observe the pressure plot and if you notice consistent pressure fluctuation, sonicate the check valve with a suitable solvent, such as isopropanol, or replace it.
3	NOTE: The eluents should be miscible and should not form salt precipitates over the range of the entire gradient. The eluents should also be properly degassed. NOTE: Due to its miscibility with water and most organic solvents, isopropanol is often the choice when removing air bubbles from an HPLC system.	Ensure that the method settings are properly set and the gradient system is delivering the correct gradient composition. Check if the mobile phase reservoirs are empty or if the filter frits are blocked. Check for air bubbles in the system. If necessary, purge the pump and system with a viscous mobile phase to remove any air bubbles. Check the system for any leaks. Check for leaking pump seals. If necessary, replace pump seals. Check for sticking check valves. If necessary, sonicate or replace check valves.
4	Leaking seals	Perform a pump leak rate test or equivalent to determine if seals are leaking. If so, replace pump seals.

21-Jun-2025