Pressure fluctuates on an ACQUITY UPLC pump after running dry with salty mobile phases - WKB248356

SYMPTOMS

• Unstable pressure
• High delta psi
• All leak tests pass
• System ran dry while using eluents with buffers

ENVIRONMENT

• All ACQUITY UPLC systems

CAUSE

Precipitated salt residue in pump

FIX or WORKAROUND

1. Prime and flush the system with MilliQ water. If necessary, backflush the column if there is a blockage that is hard to dissolve.
2. Check the delta values on the pump. Preferably, they should be below 20 psi.
3. If they are still high, put the system on low flow (0.100 mL/min) overnight.
4. Check delta values the day after. If they are acceptable, test the system further with a known sample.

ADDITIONAL INFORMATION

To prevent problems from occurring again, monitor the volume of mobile phases on the system so it does not run dry. When you are done with a sequence, either let the system run with a low flow (0.100 mL/min) or, preferably, flush the system with MilliQ water before shutting it down.