Troubleshooting retention time shifts and variable pump pressure｜質量分析計・LC-MS/MSシステムのSCIEX

For research use only. Not for use in diagnostic procedures.

Issue Description

Retention times have shifted to the right, and pump pressure is showing as higher and more variable than normal for the aqueous pump on a Shimadzu LC-30AD Nexera and EXION AD binary pump systems.

Resolution

Summary: Flow rate checks should be performed to determine whether pumps are accurately delivering solvent. Then the pump should be flushed with isopropanol to remove bubbles. The solvent suction filter should be replaced because it may be potentially clogged.

Flow rate check:

1. Deactivate the hardware profile in Analyst® software.
2. Power off the LC controller.
3. Remove the LC tubing from the HPLC column and insert the tubing into a waste container.
4. On the front panel of the pumps, press the VP button.
5. If the VP button does not show mobile phase, press “CE” followed by “Function” until “System” is shown on the screen. Then press “Enter”, “1”, “Enter”, “CE”, “CE”.
6. Press VP repeatedly until the screen shows “Validation”.                                              
7. Press “Function” repeatedly until the screen shows “FLOW CHECK”.
8. Press “Enter” and the pump will begin to pump at 1 mL/min.
9. After approximately 30 s, simultaneously start a timer and press “Enter” on the pump; measure the time to collect exactly 5 mL of water.                                                       
10. Collect exactly 5 mL of solvent and stop the timer when the volume reaches 5 mL.
11. Enter the time in seconds on the screen.                                                      
12. The measured time should be within 2% of the expected time of 5 min.
13. If the time needed to deliver 5 mL was longer than 5 min, troubleshoot to determine the source of the problem. Common causes include air bubbles in the pumps, leaks in the pump system, clogged inlet filters or pump fluid lines, and faulty check valves.

1. Remove clogged inlet filter.
2. Replace with new inlet filter.
3. Purge pumps with mobile phase (open purge valve and press “Purge” button).
4. Perform a flow rate check.

1. Change solvent line to a bottle containing 100% isopropanol.
2. Open the black purge valve and press the “Purge” button. Repeat twice after the cycle has finished after approximately 4 min.
3. Place the solvent bottle back into LC eluent.
4. Perform 2 purge cycles.
5. Close the purge valve.
6. Perform flow rate check.

1. Remove the LC tubing from the HPLC column and install an inline connector with a stainless steel plug on the end to completely seal the LC line.
2. On the front panel of the pumps, press the VP button.
3. If the VP button does not show mobile phase, press “CE” followed by “Function” until “System” is shown on the screen. Then press “Enter”, “1”, “Enter”, “CE”, “CE”.
4. Press VP repeatedly until the screen shows “Validation”.
5. Press “Function” repeatedly until the screen shows “LEAKAGE TEST”.
6. Press “Enter”.
7. The system will start pumping and once it reaches pressure, it will automatically turn off.
8. The pressure drop will be monitored. A rapid pressure drop indicates a leak somewhere in the system. The test can be performed on both pumps as a comparison in case one pump is not exhibiting problems.
9. If the test indicates a leak, check the tightness of fittings throughout the system by slightly loosening and then re-tightening each fitting.
10. Overflowing and increasing volume of seal rinse bottles is an indicator of leaky pump seals. Open a service call.         
11. Repeat flow rate check.