hi NMR salt identification. i record proton NMR spectra in dmso solvent there moisture beaks swifted around 4 ppm to 5 ppm first decide accourding spectra samples having moisture but we continues work on that still NMR spectra moisture peak swifted i doupt that may salt present in compound ,
i have doubt if salt present in molecule how we can identified ?
for that purpose i using TFA also in this spectra moisture peak swifted around 13 ppm .if any one suggest me which kind of experiment help to solve this problem
Hello Manikandan,
If you use deuterated DMSO as a solvent for the 1H NMR spectrum you shall observe two peaks due to the DMSO-d6 which are around 2.5ppm for DMSO and 3.35ppm for H2O. So when you try to deduce your sample structure make sure to remove 2.5 and 3.35ppm peaks.
If you believe that there is a salt presence then you may also try running a Mass Spectrum of the sample which would provide bit more details related to your expected structure. Hope that helps.
Residual solvent peaks: DMSO ca.2.5 and moisture ca.3.3 ppm. The moisture (water) peak will move downfield upon addition of TFA. That is "normal". Presence of "salt" (NaCl, or other) will affect the tuning of the probe. Clemens Anklin gave you good advice. Good luck in your work!
If moisture is more or presence of water, you can opt for water suppression technique in NMR. If you really want to identify the presence of salt from prep.HPLC modifiers, you can look for what type of modifier or buffer used for purifying your final compounds. according to that you can deduce your salt forming signals with the help of D2O exchange methods.
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