I got this 1H NMR chart for a compound and I was told that the line I circled in red is not from the sample, however I don't know if there's a method to adjust that in Mestrenova.
Any advice and explanation about what this line is would be highly appreciated!
Hi,
In which solvent was this recorded? And why would you like to 'edit' it?
In DMSO, I want to edit it because it's not a peak and it's not from the sample.
The peak looks like a quad detection artefact and is instrumentally generated. Whilst annoying, it represents how your data was collected and so it shouldn't really be hidden. You could always label it if you think that it is confusing.
Yes, as John said, editing data is a big no no. Everyone will understand it is an artefact, so no worries!. By the way, what is your spectral width, and are you sure it isn't an aliasing peak? While annoying, unexpected peaks can be indicative that settings are wrong.
I'm fairly certain that this isn't an aliased peak. Its position means that it would have to come from a long way outside the spectral width. It would be good to know what the SW and O1 values are as well as NS. My suspicion is that this is right in the middle of the spectrum making it a prime candidate for a quadrature artifact. These are normally caused by a DC offset and are eliminated by phase-cycling, hence the question about the NS value (too few scans will not allow the artifact to be cancelled out).
John Hollerton thanks for your answer, but where can I get these values you're mentioning and is phase cycling related to the instrument set parameters, or is it related to post processing of the raw data?
Vic De Roo I feel that you may have got my question wrong, sure I agree that "editing" data is a big no no and is unethical and I would never do that. For clarification, my question was wondering what is that and if it's related to post processing data such as baseline correction and phase correction that I maybe missing because I'm just a novice in dealing with NMR charts.
This is the image of the full spectrum to show its exact position
As I suspected. This is exactly in the centre of the spectrum and is an acquisition artefact. You shouldn’t see this and it may be worth getting someone to look at your instrument. From vague memory, there is a way of altering the DC offset of one of the channels to stop this happening. In the meantime, more scans would decrease its intensity due to phase cycling. You may also want to look at you acquisition parameters as acquiring data at -7ppm is seldom necessary.
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