my NMR system recently suffers from problems with spinning the sample. Namely, it does not regulate at the set spinning rate at all in any given period of time. The spinning frequency changes continuously and never stabilizes. I wonder what may be the reason for that? Which part of the system should I inspect in the first place looking for the solution? Thank you in advance!
All the best,
asked Mar 14 '12 at 14:29
often the problem is dirt and dust. This adhered at the spinners outside and will be transfered upon the inner turbine. And this produces often an unregulated spinning of the sample! Also buckled, twisted, warped glas tubes can cause these behaviour.
Cleaning the inner turbine is now the correct procedure.
There is a turbine implemented into the "probe" or the "shim-system" or in the "upper-barrel". This depends on the manufacture of your NMR system.
For this cases you have to be very careful and very familiar with your system.
Please give me/us a note, which system you have.
answered Mar 15 '12 at 04:44
you have to demount the "uppder-barrel". There is the turbine implemented in.
Please do the cleaning only, if you are very familiar with the system!!!!!!
First you have to mark the original position of the barrel in your magnet. Also the cabling has to be marked for the reinstallation. Also there is no sample in the tube! If you have cut off all cabling (pressure and electronics) then you can open the two screws on top of the plate. Then you can get the "upper-barrel" off the magnet.
On the bottom is the turbine. You can use wipes with a small amount sugged in Propanol-2 to clean the inner part of the barrel. DO NOT USE PROPANONE/ACETONE or other aggressive solvents!!
You can press smoothly "kim wipes" or something like this through the tube. The end part is quite narrow!!!
If it is clean and dry! You can remount all the stuff in reverse order. May be this helps a bit.
answered Mar 16 '12 at 01:50
After disassembling the upper barrel and cleaning it as described above, you should also disassemble a stranded wire and use a single strand to poke out the spin and bearing air holes in the turbine stage before you put it back together. Also while it is apart, check the bearing surface to be sure there are not any burrs of metal. If there is a burr, smooth it down with a small whetstone.
answered Mar 22 '12 at 10:48