Basic Bruker Proton NMR Tutorial
Sample preparation, insertion and removal.
Small glass vials, about 5 mL volume with caps.
Pasteur pipettes with bulb.
Filter paper with small glass funnel.
NMR tubes, 5mm, Wilmad 507-pp or better. (High quality tubes are required.)
Deuterated Chloroform (CDCl3)
Other deuterated solvents, such as d-acetone, D2O, or d-toluene depending upon the solubility of the sample may also be used.
Kim-Wipes.
HOW TO PREPARE YOUR SAMPLE:
For solid samples, place approximately 25 to 50 mg to a clean glass vial and then add about 2 mL of solvent. Mix well until the sample dissolves. Filter out any particulates or undissolved materials. Add about 0.5 to 1.0 mL of the liquid to a clean NMR tube and cap.
For liquid samples, place approximately 1 drop into a clean glass vial and then add about 2 mL of
solvent. Mix well and filter out any particulates or undissolved materials. Add about 0.5 to 1.0
mL of the liquid to a clean NMR tube and cap.
INSERTING THE SAMPLE INTO THE PROBE:
DO NOT FORCE ANY OF THE FOLLOWING STEPS, BE SLOW AND GENTLE!!!
The availability of sample spinners is limited for this instrument, and they can be easily cracked, broken or worn out by misuse. Additionally, NMR sample tubes can be easily broken and present a safety hazard. If you have problems, get your lab instructor to help you.
Hold the plastic spinner vertically with the reflective strips up and press the sample tube GENTLY down through the spinner about two-thirds of the way up the tube. Twisting the tube a little helps. Then lower the tube and spinner into the clear plastic spinner depth gauge. Now GENTLY adjust the sample tube down until it stops. The liquid level should be approximately centered about the reference line on the depth gauge. Adjustment of the spinner depth is now correct. Lift the sample tube out of the depth gauge by the top and GENTLY wipe off the lower portion of the tube using a Kim-Wipe.
Remove the dust cover from the probe on top of the magnet. Press the 'Lift On/Off' key on the NMR control pad. After the lift air is heard and felt at the top of the probe, grip the sample tube above the spinner (reflective strips up) and gently place the sample spinner in the probe -- it should float on the lift air.
Press the 'Lift On/Off' key on the NMR control pad to lower the sample into the probe, then
replace the dust cover on the probe.
REMOVING THE SAMPLE FROM THE PROBE:
Remove the dust cover from the probe on top of the magnet. Press the 'Lift On/Off' key on the NMR control pad. After the lift air is heard the sample and spinner will rise to the top of the probe. Grip the sample tube above the spinner and gently remove it from the probe.
Gently pull the sample tube out of the top of the sample spinner (twisting a little helps) and place the sample spinner back in the box atop the instrument cabinet.
Press the 'Lift On/Off' key on the NMR control pad to switch off the lift air. Replace the dust
cover on the probe.