It is a heteropolysaccharide that I have. In spite of high concentration and purity it's been difficult getting a good C13 spectra. Any suggestions will help.
Dear Moumita Patra,
what would be the purpose of adding a drop of CDCl3 or DMSO-d6? Providing an internal chemical shift reference? CDCl3 would not be very soluble in D2O. And I don't think it would improve the quality of the spectrum.
I am curious to know where you got the idea.
Regards,
Ludger Ernst
I agree with Professor Ludger Ernst and look forward to your answer.
I imagine the reason this may have been suggested to you is to ensure accurate chemical shifts. Your spectrometer will reference using the deuterium signal from D2O, however the exact frequency will vary with temp (approx. -0.011 ppm K-1).
CDCl3 will not be miscible with D2O, so I would not suggest trying that.
If you have DSS ( 4,4-dimethyl-4-silapentane-1-sulfonic acid, delta 0 ppm) this might be a better way to go. You could have this internally in your sample by making a dilute solution of DSS in D2O. Note: the definition of 'dilute' will depend on how concentrated your actual samples may be.
Yes, DSS (water soluble) would be a good choice and keep concentration as you would be using the TMS as reference standard!
Prof. Ernst, Prakash Parajuli, Pedro Aguiar, Riaz A. Khan, thank you very much for your kind suggestions. As Prof. Ernst suggested, the instructor who runs the NMR instrument wanted me to add it as an internal reference. I was concerned that, on adding d6-DMSO would I be able to correlate my proton and C13 spectrum?
To make things clearer, I have acquired proton spectrum in D2O, and the C13 one adding a drop of d6DMSO to the same tube.
Thank you again..
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