Ghost peaks and sudden baseline shifts

5975C MSD and 7890 GC. I am fairly new to GC-MS and am having issues with my baseline. I have recently begun seeing ghost peaks and sudden baseline shifts after replacing a column. I did inlet maintenance and added an in-line gas purifier as well as conditioned the column to help resolve, but the bottom spectra which was run after this maintenance is actually showing the ghost peaks again as well as the sudden baseline shifts I saw before. 

Could this be a detector issue? I have a CI detector but know nothing about how to clean or troubleshoot it. 

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  • We're using UHP helium (something like 99.99995% pure?).

    Yes, it is an old column. The other column I was using broke in the middle, so I had no choice but to install this backup column. Ordering a new column is on my list of things that need to be ordered.

    I did give both column nuts a tweak and ran a blank run. Ghost peaks are better now, but I am still getting a few at the end. N2 numbers are also down. I'll continue to tweak and see if I can get the N2 numbers even lower.

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  • We're using UHP helium (something like 99.99995% pure?).

    Yes, it is an old column. The other column I was using broke in the middle, so I had no choice but to install this backup column. Ordering a new column is on my list of things that need to be ordered.

    I did give both column nuts a tweak and ran a blank run. Ghost peaks are better now, but I am still getting a few at the end. N2 numbers are also down. I'll continue to tweak and see if I can get the N2 numbers even lower.

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