- Only Wilmad or Norell tubes should be used. For the sake of your spectra and the safety of our instruments I strongly discourage using generic tubes
- Always use a cap
- Never use a tube which has cracked or broken in any way, including chipping at the top. These are much more likely to shear
- If you dry tubes in an oven, do not place upright in a beaker or tube rack. Always lay the tubes flat (see here)
- All of our instruments use 5mm tubes
Tubes should be purchased directly from one of the manufacturers linked above as opposed to through a third party. This should result in a substantial savings. For instance, a 507-PP-8 tube directly from Wilmad costs $9.20 (not including our academic discount) while a 5 pack of the same tube from a well-known third party costs $56.20 (not including any discounts).
You have a choice of 7,8, or 9 inch tubes. All will work fine. I personally prefer 8 inch tubes. Two considerations: use a 9 inch tube if you are going to flame seal your tube; and you should consider a 7 inch tube if you plan to use a pH meter for solutions within a tube (some nmr-specific pH meters are rather short and will not submerge in a solution of appropriate volume in a longer tube).
I recommend purchasing tubes from Wilmad. We receive an academic discount of 25% along with free shipping. Which tubes you purchase depend on what you will be doing:
|Wilmad||Norell||Class of Glass|
|Routine experiments (mildly superior lineshape)||WG-1226-8||$4.47||506-P-8||$5.48||A|
|Variable temperature (mildly superior lineshape)||507-PP-8||$9.20||S-5-300-8||$7.52||A|
|Water suppression/mutli-dimensional experiments||528-PP-8||$13.94||S-5-500-8||$15.04||A|
Cleaning / Drying
Please see Wilmad’s technical document NMR-010 for details on properly cleaning your tubes. Of great importance to our spectrometers is the following excerpt:
“Drying tubes at elevated temperatures can reshape and ruin precision NMR tubes. If you dry tubes in an oven, WILMAD recommends placing tubes on a perfectly flat tray at 125oC for only 30-45 minutes. Better is the use of a vacuum oven that will remove water at lower temperatures. In a flat position, tubes that do reshape could be out-of-round and may not fit the spinner turbine as well. But they’ll not affect the spectrometer probe adversely. Tubes placed in an oven in a beaker, flask, or tube rack can bend, increasing Camber (lack of straightness). Bent tubes may still fit the spinner turbine, but can damage or break the NMR probe insert, a costly repair with many probes.”