Agilent 6120 ESI Tune losing signal for high MW


Comparing my tune signal now and months and years ago, I see a drop in signal. It used to be in the 300.000 for low mass and 50K for high. Now I have 50K for low and very low (~1000) for high. Last time only 290 for the high mass (see report attached).  So the Tune passes, but I must lose sensitivity.
I cleaned the capillary, and it did not help too much.
How should I proceed?
- clean ion funnel?
- clean optics?
- get a new capillary?

Any advice?

Thank you

  • Dear Andy

    Thank you for your reply.

    I run also autotune and I got similar results.

    What would be the best way to troubleshoot this issue?

    1. I will replace the Tune Mix and check the tune again.

    2. If this does not fix it, then I assume I have to clean ion optics assembly?

    3. If this does not fix it, clean the high-energy dynode.

    4. If this does not fix it, replace the electron multiplier horn

    From the manual (G1960-90154_SingleQuad_Maintenance.pdf), it is not clear where the electron multiplier is located. Are there better instructions I can follow?

    They only provide two images, without context on how to reach it:

  • In the autotune report, you should see a set of tune values.  The EMV value would indicate whether this component has reached the end of its life.

    The multiplier is located inside the vacuum chamber.  If you want to do this yourself, start on p81 of the maintenance guide that you mentioned.


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