My work is on marine sponges and I have isolated few compounds from them .I have performed only NMR and LCMS for the isolated compounds, as the isolated compound quantity was less.
Can I get any idea about my compound from this two analysis alone?
Is it possible to find the compound present in my sample only with NMR results?
Can anyone clear my doubt?
The answer is certainty comes from the quality of the data and also whether the compound is known or unknown in the literature. If someone had found the same compound in the same matrix as you have using the same analytical techniques, great! You just confirmed the other person's results. It is still possible both of you could be wrong, and if that were true, the person challenging the answer would have to make a compelling case based upon the preponderance of the newly presented evidence.
If you claim you have discovered the same compound in a new matrix, using the same techniques already published in the literature to determine it would mostly suffice.
Also excellent if your standard (of a known compound) matches that in your NMR and LC-MS results.
If there is no standard and/or if you are claiming an entirely new compound has been found, then the criteria for publication of the results are necessarily significantly higher. Of course the value of the publication in the peer-review community is greater when in fact a compound detected actually is an entirely new compound or even a new class of compounds. . .
Therefore hope you find multiple new compounds very difficult to identify, well worth the level of doubt generated in the analysis, and that the new compounds are subsequently found to have important biochemical and/or even biomedical properties. Cannot know until after all the difficult and challenging work has been completed whether successful.
Our lab identified a-endosulfan correctly after 30 years in the literature incorrectly identified. The more important the chemical, the bigger the deal if it is properly and correctly identified.
Walter.
Sir thanks for your comments.
My doubt is almost cleared. As I had less quantity of the isolated compound , I could not do any more analysis to confirm the compound.
The only way for me is to find the compound using these techniques only, once I get any idea regarding the compound I shall go for literature reference which carries results similar to my isolated compound.
Excellent. Much patience is require to collect, concentrate, and purify any compound of interest. The better and more careful you analytical technique, the less often doubt will show up. The NMR is great because one can often see the purity of the sample just from things like the relative peak integration values and the presence of peaks spread along the baseline that do not have the proper stoichiometry to be the parent / main compound.
I use HyperChem which is available for a reasonable fee for students/grad students. It can includes an NMR routine for spectral interpretation. It also includes a vibrational spectroscopy calculation routine in which one proposes a chemical structure and then estimates an IR/Raman spectra of that compound. Spectra analysis like running is something most individuals can do to get from A to B. As structures become more complicated, need for training commeasurate with the demand is required. Sprints are cool, and solving an individual structure elucidation problem first is always an major accomplishment. To be seriously in the running, need to see this as a marathon thing.
Train for solving the most difficult / longest to solve structural problems, and race to solve individual structural problems whenever they show up.
Finding people who do spectral interpretation is difficult sir.Many refuse to do interpretation using these two techniques alone.They require some more additional analysis results for interpretation, which is difficult in my case.
It is like learning geometry or calculus. Not something you are unable to learn.
Please learn for yourself as much as you can about interpreting NMR spectra, including 2D NMR. Often that [plus maybe molecular weight and molecular formula] can be sufficient in and of itself. And if not very close to the right answer. If the NMR interpretation is incorrect, impossible to have the correct chemical structure.
Thank you sir , for ur valuable suggestions ,will proceed accordingly.
Depends on the quality of your spectra and also if it is a known compound. You can start from the kind of compounds usually find in the species you are studying so you can reduce the amount of literature to search.
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