Elevated baseline and continuous baseline trend

I am a new GC/TQ user. I am using a GCMS 8890 with a 7010B TQ system.  I recently changed the column on the GC and ran some samples, I am continuously getting an elevated baseline, to cross out contamination, I have baked the column twice. Also, my baseline towards the end elevates as can be seen in the image attached. The masses are also given underneath. 


  • The peaks are huge and the background is gigantic. The first thing is to inject much less sample. Your peaks are 50M counts tall when, if it's running properly, they only need to be 50,000.  Certainly all of them should be <3M tall or so.  Too much sample makes a mess inside that you have to clean up.  The 7010B High Efficiency Source is best used running very small amounts of very low concentration samples. That saves you GC inlet and column maintenance and MS ion source cleanings and EMV replacements.

    What column is it? What is the column maximum temperature? How close did you get to that max when you baked the column?  What flow rate?  What carrier gas?  What are your GC and GCMS parameters?  Are you running in MS1 Scan or MS2 Scan ?  

    The ions out there are probably column bleed related - the column has damage from oxygen, heat, solvent, or some combination and the spine of the cross-linked phase is coming off.  If you look at the spectra along that plateau and the ions are all the same, that's the problem.  If you look along there and it changes - especially if the farther right you look the ions get heavier and heavier, then it might be actual contamination. 

    Please share back a tune report and the answers to the questions above.

Was this helpful?