The only really effective way to degas samples for NMR is by using the Freeze-Pump-Thaw technique. Sometimes it may be sufficient to flush the space above the sample surface with dry nitrogen or argon. This must be done with great care to avoid blowing the solution out of the tube. Bubbling nitrogen through the solution is not considered an effective way of removing oxygen, and may waste costly solvent through evaporation. See attached articles. Best of luck in your research!

Thank you Dr. Hamada and Dr. Foris for your valuable suggestions. I'll read them. Degassing ordinary nmr tubes (5-10 mgs of sample, 5mm OD tubes) is manageable. Problem arises when I need to degass a micro nmr tube with less than a mg of sample and need to insert the inner tube after degassing. These special tubes are very delicate and costly. I was in bad situtaion at advansed stage of synthesis where sample is very scarse because tube broke during degassing. So, I need to find a correct technique to avoid this in future.

Thank you so much.

Hey Toufiqur Rahman,

I measure NOE-spectra without degassing. If your T1-time is long enaugh, about >0.5 sec it is no problem to measure NOE's. The degasing helps to encrease the T1-time. If the T1-time is much less

Dear Dr. Elend,

Thanks for your suggestion. I'll certainly try that. My molecules are alkaloids or alkaloid intermediates with MW of 340 to 700.

Thank you