What about to use an external capillary filled with deuterated solvent?

Normally deuterated solvents are less efficient than normal solvents. You may try to warm gently in a water bath (45-50° C max) the deuterated solution. Otherwise you may try to work with a less concentrated sample. On a 400 MHz instrument it is possible to obtain a good spectra using 10-15 mg of substances.

Thank u all

Try dmso-d6

You can try CDCl3 or DMSO-d6 or Acetic acid-D4

Thank you ^^