Pressure pulsation or inconstant pressure

Possible Cause

Remedial Action

System clogged with particles

Samples and insufficient solvent purity are frequently the source for particles clogging the system. In nano LC and capillary LC applications, the capillaries with even smaller inner diameters need an even higher level of solvent and sample purity.

  • Nano LC and capillary LC applications:

    To avoid contaminating the sample, do the following:

    • Use the vials with particle-free septa from the ship kit or those listed in Recommendations on Vial Caps and Well Plate Covers.

    • Reduce the number of replicates from one capped vial to <10.

    • Wash the needle and/or intensify the needle wash in the chromatography data system.

  • Run the script: D01 - Test System Back Pressure. Follow the instructions.

Solvent is degraded

Use fresh solvent.

High backpressure

Possible Cause

Remedial Action

One or more capillaries in the system clogged or damaged by bending

Run the script: D01 - Test System Back Pressure. Follow the instructions.

Column contaminated or clogged

  1. Run the script: D01 - Test System Back Pressure. Follow the instructions.

  2. If the test succeeds, the column or the capillary to the down-stream device is clogged.

  3. Replace the column or the capillary to the downstream device.

Column switching valve clogged

  1. Check the valve for indications of blockage.

  2. Replace the valve if necessary (see Replacing the Vanquish Switching Valve or Replacing the VICI Switching Valve).

Pre-heater clogged

Replace the pre-heater (see Replacing the Passive Pre-Heater).

Contamination in the system

Flush the system by purging the pump and the autosampler with an appropriate solvent.

Needle seat clogged

If the backpressure test script returns the message that there is a high backpressure in the needle seat, run the script: C21 – Clean Or Replace Needle Unit And Seat with the parameter: Clean Needle Seat.

Solvent in solvent reservoir does not match the solvent setting

Change the solvent in the solvent reservoir or change the solvent setting.

Low backpressure

Possible Cause

Remedial Action

Leak in system

Run the script: D02 - Test System Tightness (What Should Be Tested = System). Follow the instructions.

Air trapped in the autosampler

Run the script: C04 - Purge Sampler.

Solvent in solvent reservoir does not match the solvent setting

Change the solvent in the solvent reservoir or change the solvent setting.