Sample Tubes

Tube Considerations:

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

Purchasing

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).

Recommendations

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
Application	Item	Price	Item	Price	B
Routine experiments	WG-5MM-ECONOMY-8	$2.02	ST-550-8	$1.90	B
Routine experiments (mildly superior lineshape)	WG-1226-8	$4.47	506-P-8	$5.48	A
Variable temperature	505-PS-8	$5.64	S-5-200-8	$4.78	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.”