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    Hi, I was wondering why dont people use H2O in NMR spec and cancelling out the peaks (they should be the same all the time?) instead of using the much dearer D2O. p.s some guy used H2NO3 as a solvent for NMR in our lab the other day -.- .
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    (Original post by cllio)
    Hi, I was wondering why dont people use H2O in NMR spec and cancelling out the peaks (they should be the same all the time?) instead of using the much dearer D2O. p.s some guy used H2NO3 as a solvent for NMR in our lab the other day -.- .
    Overpowers the signal of all other protons in the spectrum. Also will give a broad peak which will smother other peaks in the spectrum.
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    Same reason why you don't use any protonated solvent for proton NMR-the solvent peak dwarfs everything else.


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    What everyone else said.
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    but it going to be the same peak all the time isn't it? like pretty much exactly the same so why can't you just cancel it out? just make an algorithm for it
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    (Original post by cllio)
    but it going to be the same peak all the time isn't it? like pretty much exactly the same so why can't you just cancel it out? just make an algorithm for it
    You'd need an exact quantity of solvent each time. This is not realistic at all. It is possible in IR as you use the same sample salt plates each time and calibrate regularly.
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    Apart from the gigantic H2o peak in the spectra... how many organic molecules are soluble in H2O? Hence usually use CDCl3 or deuterated DMF or DMSO
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    (Original post by cllio)
    but it going to be the same peak all the time isn't it? like pretty much exactly the same so why can't you just cancel it out? just make an algorithm for it
    I guess you've never run an NMR sample of a decidedly wet product. The water peak can be very broad and it is easy for several peaks to be lost underneath it.

    Also, as everyone else has said, the ratio of solvent peak to product peak would be insanely large and you could not calibrate the machine without knowing exactly how much solvent was used.
 
 
 
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