There are several thougts, as the reasons can be different: bad sample, improper VT conditions (unstable temperature, incrorrect gas flow), Topshim miscalibration or even dirty or cracked insert glass. Set normal temperature (298-303K, 400-550 l/h gas flow, run VT selftune). try with standard sample (1% CHCl3 in Acetone) or even run Topshim 3D with 2mM sucrose sample. If final B0 Std.dev (after 3D) is below 0.5.0.8 Hz Hz your probe is most probably OK. check sample position in spinner and solvent height - are them ok? Maybe, in contrary, too much solvent and experiment is on elevated temperature?. Try extra parameter convcomp (convection compensation).
Works under stable VT conditions (also check. The last, but not least: sample homogeniety. Solid particles, high viscosity, aggregation? Dear Ferron, please provide the topspin version, you can start trying with 'topshim gui' select 3d shim and use 10% d2o and 90% h2o sample, after finishing save this shim. Now put line shape and then try the 'topshim' only. If you see the improvement then do a little bit manual shimming of z, z2, z3. Depends your spectra -how it's shape showing.
Topspin Nmr Cracked
We do this as part of our weekly maintenance with a doped ASTM standard, which also affords us easy access to quickly calibrating carbon 90-degree pw's. Not to bring up a dead topic, but I've been having this issue as well. Here's what I did to solve it. First make sure topshim is using the correct solvent by running 'lock' from the topspin command line (silly, but this took 2 hrs for me to figure out). 2ff7e9595c
Comentarii