High moisture content in GCMS

During tuning my GCMS has high moisture content, but it is free of oxygen and nitrogen. The moisture filter is also ok, I also replaced the helium gas source, but the problem still exists.

Please  suggest me any probable causes?


  • Hi

    Which model you are using?

    Can you share tuning report.

    Any recent maintenance performed, if, yes, then what consumables replaced.

    How is inlet of gc, is it okay

    How is split vent filter?

    First make sure GC side, everything is okay then can go to see MS..

    But share tuning report to understand better...

  • Hi,

    It is 7000D model. There is no any maintenance performed. It is a new system just after installation. So, the split vent filter is supposed to be clean..

    I attached the tune report for your reference.

  • Hi

    Do baking of MS then check.

    I think after baking, moisture will go down from 125%.

    If not, then we have to do maintainence of GC first then check and at last we have to focus on MS.

    As per my experience, baking of ms should solve this moisture problem...

  • Please turn on the Collision Cell Gases. They must be on during tuning and running the QQQ system. On a 7000x system, the Helium should be 2.25 ml/min and the Nitrogen should be 1.5 ml/min.  It takes fifteen minutes or a bit longer for the Collision Cell temperature to equilibrate after the flows are changed, too, so be a bit patient for best results.

    The air/water test is invalid without them being on and stable.

  • Hi,

    I turned the collision cell gases on, and waited for long hours even days, but there is no significant difference on the moisture content. I attached the report for your reference. By the way, is it necessarily required to tune with the collision cell gases for scan mode of  analysis.?

  • Hi dag,

    Try varying the column flow to see if the moisture goes up or down with the changes. I have seen where a saturated gas trap will start bleeding moisture into the system. 



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