Using GC-FID an unknown peak consistently appears in our reactions. The blank shows no peak other than the solvent peak (CHCl3). Using the same sample, column and GC parameters on a GCMS the peak does not appear. Both CI and EI have been used with no results. Why is this unknown peak being detected by the FID but not MS? Is it not being ionized?
I made the experience that the FID is more sensitive to not or little substituted hydrocarbons, so maybe if the peak is very small when using the FID and for the MS it might just be under the limit of detection.
Apart from that i have to agree with the two posts before that it's hard to guess where the problem lies.
Are there other differences in the chromatograms? Are the chromatograms overlapping and just this one peak is missing?
To quote Rod's law, the more you don't tell me the more I am unable to help you. Where does the peak occur? Is it reproducible? What are your chromatographic conditions? There are multiple reasons that peaks could occur using an FID and not show up on GC-MS, but my crystal ball broke many years ago and therefore you actually have to give me information for me to help you.
Fully agree with Mark. Besides the use of CHCl3 as solvent we know nothing about your experimental setup...
Instictively, I'd say that you are having chromatographic issues more than a detection "mistery": it is much more probable that FID doesn't see something seen with MS, but my crystal ball is gone, too...
I made the experience that the FID is more sensitive to not or little substituted hydrocarbons, so maybe if the peak is very small when using the FID and for the MS it might just be under the limit of detection.
Apart from that i have to agree with the two posts before that it's hard to guess where the problem lies.
Are there other differences in the chromatograms? Are the chromatograms overlapping and just this one peak is missing?
I think as Florian said its about the limit of detection of FID and MS.
Hi Everyone!!
I am attaching the gas chromatography analysis report here.
The shape of peaks in my calibration report doesn't look fine.is'nt it?
What in your opinion is the reason
1) of these irregular peaks?
2) Why the shape of baseline in detector 2 is not smooth near Nonane(time=36.6)
3) Reason of variation in response factor deviation in every calibration (of 4 heavy hydrocarbons in detector 2)
Will be grateful ,if anyone can help!!
OK, you're going to have to do a LOT of explaining. Exactly how are you detecting nitrogen on your FID? (Hint, you're not). Gonna be really hard to match up peaks and systems if you can't even describe the analytical system you are using.
Ne R.Z You have dropped your question into someone else's answer thread. You need to ask a new question of your own.
Ne R.Z You must post a new question of your own, You will not get anwers to your question if your question is in the answers thread of another question.
- Badges
- Science method
- Similar topics
- Chemistry
- General Biochemistry
- Biochemical Techniques
- Analytical Chemistry