by
NZBen » Tue Aug 31, 2021 9:39 pm
Thanks for the thoughts so far, a couple of things I negated to mention...
I conditioned the fiber for an hour at 300C before use, I suspect the horrific tailing peaks are caused by an inlet condition (I think I need to cut and reinstall the column into the inlet). I also ran a condition on the column and a bakeout on the MS. Water shows quite high in the MS (around 18% - other gasses are low, around 0.5-3%)
At the moment I'm not concerned with the tailing peaks, they match the NIST spectra very closely and are compounds that would be expected to be present in the sample. I can fix the long tails later. My prime concern is the sharp peaks. They do not match the NIST library, the number one option is miles off when you compare them side by side, they are also unexpected compounds. I've had an RFPA difficulty error previously, so I suspect the sharp (good looking) peaks are an artifact caused by an electronics problem or chamber pressure (am hoping it is the high water content to blame). I don't have an ion gauge, but the foreline pressure is around 30mTorr. (makes me feel nauseous just saying that - why do they use such horrific units?!?!?) I figure with the foreline being at that level, the chamber pressure should be ok? The pump is a diffusion pump with good clean oil.