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- Posts: 2
- Joined: Tue Jun 14, 2022 9:36 pm
I ran standards for both, did an overlay, and confirmed that the sample had a peak at where the standard for trans-sabinene hydrate came out, but when I checked the spectra for the standard, it too had changed to look more like y-terpinene.
Basically without change to tune, gas, or literally anything that I'm aware of, during a sequence of samples running overnight the main identifying 43 m/z of trans-sabinene hydrate dropped down to a point where it was no longer identifiable by spectrum.
Here's a picture with the two spectra of that compound for comparison. Top was from the standard I ran early on, bottom is what I started getting and haven't been able to resolve:
https://imgur.com/qIXTtLm
There was a drop in sensitivity when this happened so I figured dirty ion source, cleaned it, got it all back up and running with autotune, seemed good and re-ran the standard but nope. Aside from the sensitivity issue being resolved, the spectra looks just as bad as it did before.
Any ideas as to what it could be? I'm assuming it's not anything on the GC side since the retention time for peaks in the chromatogram are unchanged.
Also to note, the standard for 1,8-cineole looks just fine, and some other standards like nerolidol do not look fine, so it's not necessarily a specifically 43 m/z issue, nor is it a single compound issue. It's just that the primary compound I'm using as an example was the first time I noticed the change and the easiest one to test quickly since it elutes within 10 min.