Sunday, October 29, 2006

Why is NMR software so important?

If you have no NMR spectrum to inspect, NMR software is not for you. That's the only exception I know. In all other cases: can you explain what your computer is for? For transforming you into a clerk? I suppose you are a scientist, that you use your computer to examine your data, to operate on them, to speculate about them...
The best thing about your computer is the sense of relaxation it can inspire: you are at your desk, seated, you can take your time... you are not distracted, your time is not limited, the ideal situation to study, to make discoveries... is it the same at the spectrometer?
NMR software is also good for your spectrometer. Let's say you have borrowed an hour of processing time from a colleague of yours. The spectrometer is acquiring a spectrum of his. The computer crashes, acquisition is interrupted... not the ideal situation. It doesn't happen anymore, but is it so necessary to run the risk? Aren't there any alternatives?
The great thing about NMR (compared to other analytic techniques) is that it is often possible to explain everything you can see into a spectrum, to assign all peaks, to translate all the spectroscopic information into a chemical information. Sometimes it happens that a spectrum is interpreted erroneously. It happened to everybody. It happened to me countless times. The chemist must do something to avoid an incident like this. My first rule is to try to explain everything of each spectrum. If, for example, a chemical shift looks unusual, probably the compound is not the one expected. If a single peak has not been assigned, it may belong to an impurity, but even this fact must be rationalized. When I can explain everything, I am confident about my conclusion. So the intermediate goal is to assign all peaks and explain it all.
The common practice to achieve this goal is to print the spectrum, maybe 10 different expansions of it, and study the spectrum on paper. This practice is wrong for many reasons:
1) You can print properly a spectrum only after you have already interpreted it.
2) If you annotate the spectrum on the screen, rather than on paper, it will be more readable for other people. The annotations will automatically appear on all future prints.
3) A good software lets you interact with your spectrum, paper does not.
4) Although most of the programs I have seen can't show a spectrum on screen with the same quality they can print, I know at least one notable exception. The pictures shown at are enough an evidence.
I understand that many of you don't like your current software. The purpose of this blog, indeed, is not convince you to use NMR software, but to show how the software currently available is not up to the task. There is work in the area. TopSpin is a great improvement over Win-NMR. iNMR is a great improvement over SwaN-MR. MestreNova, the forthcoming substitute of MestreC, still under development, claims to be a revolution. All these program appeared too late (or haven't appeared yet). Most of the software in circulation is painful. Because of the natural resistance to changes, many chemists will stick for years to their outdated, ugly, crappy programs. Eventually they'll try to convince you that theirs is the correct way to process NMR spectra...


At 1:10 AM, Anonymous Anonymous said...

we are waiting for mestrenova... the date of release was 15/11 but it isn't ready!!!



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