A Beginner’s Guide to Simple NMR Experiments in xwinnmr

 

This guide is designed more to remind beginners of the basic steps in setting up and running NMR experiments on our Bruker systems.  The steps outlined here are by no means complete, nor are they comprehensive in any way.  It is NOT designed as a training manual, and appropriate training should be completed before using these instruments.  ANY problems or questions should prompt the user to immediately stop what they are doing and contact an experienced user before continuing.

 

Commands to be entered at the xwinnmr prompt are as follows:

 

Ø      expt

 

  1. Launch xwinnmr by typing xwinnmr at the unix command prompt.
  2. Check the temperature setting on the NMR instrument.  If the instrument is not at the desired temperature, enter the following command, substituting ‘xxx’ for the desired temperature in DEGREES KELVIN.

Ø      teset xxx

  1. Display the lock level:

Ø      lockdisp

  1. Remove the cap from the NMR instrument if necessary. 
  2. Turn the lift airflow on by pressing the LIFT ON/OFF button on the manual NMR control console (top left corner of the console; the green LED should turn on after a moment).
  3. Place the NMR sample in the spinner, using the depth gauge to set the appropriate depth of the tube.
  4. Place the tube/spinner assembly in the sample insertion port.
  5. Turn off the airflow by pressing the LIFT ON/OFF button again.
  6. Replace the cap.  DO NOT REPLACE THE CAP ON CRYOPROBE INSTRUMENTS.
  7. For standard 10% D2O samples, lock the instrument by typing:

Ø      lock h2o

  1. Once complete, open the gradient shimming window for automated shimming:

Ø      gradshim

  1. Check that the username box in the gradshim window is YOUR username, and shim until you are satisfied.  Check with an experienced user for advice about parameters.  Close the gradient shimming window once done.

    2.
  2. Tune and match the electronics to the magnet PROTON frequency.  Start this process by typing:

Ø      wobb f1

Ø      a                                  <goes to the acquisition window>

The tuning and matching are then done manually, as was demonstrated during training.

  1. Load your single 1H pulse experiment.  Programs are accessed by typing

Ø      search

  1. Calibrate your proton pulse.  I usually use ‘gs’ for continuous pulses and look for the 2π pulse (~40 μs) on these instruments.