Ion at every mass

Hi 

I have a 7890/5975C that has scans that come out like this. This started months ago. I have cleaned the source, inlet, replaced the copper tubing for my carrier gas and checked the manifold many times. My tune report looks normal aside from a bit of moisture. I haven't been able to find any leaks. Multiplier gain is low. Filaments are new. Ions also appear in the TIC as well. Where could this be coming from? I've capped the detector and it appears to go away. Could this be an issue with the electron multiplier? Am I missing something? This is a relatively new instrument to me. 

 

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  • The spectrum in your picture is down to 10.  40-550 is pretty typical, although there's probably very little response to ions bigger than 400 amu or so.  

    The required threshold will be different on each instrument depending on age, cleanliness, application, concentration of the peaks of interest - many factors - and could even be different on each instrument with each tune if you want to get really down in the weeds.

    Would you be willing to share a chromatogram and a spectrum that shows your worry?  The tune shown above only has 166 peaks in it. A peak at every mass would be >800.  The spectrum shown above is scanned down to 10 with a very low threshold.

    You titled your post as "Ion at every mass" and I don't see it, so trying to help!

  • This turned out to be an issue with the column. I replaced it and the problem went away. Sorry for the late response. Thank you! 

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