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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: xshadow on April 07, 2025, 01:11:42 PM

Title: SSNMR iusse in spinning rotor (13C CP-MAS)
Post by: xshadow on April 07, 2025, 01:11:42 PM

Hi!!! I have I iusse with some analysis in SSNMR. When I try to spin the rotor (3.2mm - NMR geo 600 MHzl) at 12 KHz (3.2mm) the rotor doesn't spin correctly and I have to stop the spin in order to avoid any damage....this happen with saccharine and magnesium stearate.

When I unpack the rotor I see the top cap (the one "brown" with the "wings to spin") full of powder of the sample (very srtange!)...but usually, when it works, the space inside the top cap is empty...

Any ideas?
Thanks

Title: Re: SSNMR iusse in spinning rotor (13C CP-MAS)
Post by: marquis on April 07, 2025, 02:12:59 PM

I envy that nmr.  We only had a 200 mhz and it wasn't a solid state nmr.

Have you checked the sample tubes?  They need to be perfectly straight.  If not, that kind of problem happens.  We would normally put a sample tube on a clean, absolutely flat surface. Then you put your hand on top of it and gently roll it across the surface.  It should roll evenly.  If the tube wobbles, or makes some weird movements, throw it away and get another one.  It probably won't spin evenly in the nmr.  The tube should roll evenly.  If it passes that test, try it in the nmr.  Even one failure in a lot makes the whole lot suspicious.  Other than that, check your air lines and look for clogs.  Good luck!