Technical Information

Concentricity is measured as the difference between two radial centers obtained by using the outer and inner tube's circumference as reference points. Large values indicate tube wall dimension variation around the circumference, leading to magnetic field non-homogeneity, especially when the tube is in spinning mode.

Camber is a measurement of the degree of curvature of the tube with respect to the tube’s radial axis. Large values cause the sample to wobble when spinning and potentially damage the probe’s radio frequency coil by contact. Also, it is the major source of spinning side bands and increased shimming times.

Modern NMR spectrometers have auto-shimming routines that are applied to every sample introduced to the magnet. However, if a tube's concentricity and camber vary significantly from one tube to another, the amount of shimming time required to correct for tube variations significantly impacts the overall analysis time of a run. Since spectrometer time is precious, and most users are on a tight schedule to complete their assignments, increases in analysis time due to faulty NMR tubes is not an acceptable option to the end user.

Some brands have OD inconsistencies, especially disposable tubes. Norell’s manufacturing process minimizes tube to tube OD variation. Spinner turbines can also be worn out and need replacing or can have worn out o-rings. Spinner turbines also vary considerably in bore ID, since they are not manufactured as precise as glass NMR tubes.

The Select Series™ NMR tubes are manufactured out of ASTM Type 1 Class A borosilicate glass, known in industry as Pyrex ®, Kimax ®, or Duran ® glass, and are specifically designed to be used for high resolution NMR. They are recommended for chemical structure determination, low and high temperature applications, low temperature sample storage, and more. Select Series™ offers the NMR Spectroscopist the ultimate in quality, durability, and performance.
 
The Standard Series™ NMR tubes are manufactured out of ASTM Type 1 Class B borosilicate glass, and are designed to be used under ambient temperatures for chemical reaction monitoring, high through-put NMR and for general student use, where cost savings are important.

Yes, but at a cost of increased shimming times and possible degradation of the NMR spectrum. However, for routine NMR or for scouting purposes, low end or disposable tubes are used quite regularly in high-end spectrometers.

We recommend the “Select Series” branded NMR tubes, since you could be using various methods, such as temperature gradients, spinning, freezing, 2D, 3D or more, etc. to obtain a desired spectrum.

The use of the “Standard Series” is sufficient. Many open access NMR spectrometers are used to check the status of a chemical reaction and users tend to use medium to low cost sample tubes for this type of work. Since the molecular structure of the product compound(s) has long been determined through Mass Spectrometry and high resolution NMR or X-Ray spectroscopy and other methods, the use of high resolution NMR for monitoring chemical reactions is superfluous.

All of the Norell Brand NMR tubes are manufactured using a processes that uses no lubricants, organic solvents, or inorganic reagents. Inherently, Norell NMR tubes are completely free of metal and organic impurities that would lead to sample contamination and/or background signals.

Heat the tube about 1-2” from the open end with a Bunsen burner, turning gently while pulling the end glass piece off. Constricted NMR tubes are an easier choice for you, since the constricted portion requires less effort to close.

It is best not to exceed 60 deg C. At higher temperatures, slight tube distortion can occur which will effect tube camber. If you wash NMR tubes, we recommend a final rinse with a solvent that easily evaporates at 60 deg C and that has no residue.

Calculate using the formula:

P(max) = (tube wall thickness in mm/tube O.D. in mm) X 2,000 psi

Example : 0.38mm/5mm X 2000 psi ≈ 150 psi

Place your sample into a Fluoropolymer NMR tube liner, and place liner into a 3-4” long glass NMR tube that is open on both ends. Place a rubber o-ring around the top open end portion of the liner to prevent it from slipping through the glass NMR tube. Position the glass NMR tube into a spinner turbine, and place into magnet. The rf coil will only “see” the Fluoropolymer liner and sample, since the glass tube portion is too far from the coil to be detected. We recommend the Norell Fluoropolymer NMR tube liner # TL-5-7 with a 3 to 4” long open-ended glass NMR tube (we can make these for you).

We recommend the use of quartz NMR tubes, since the Boron content in quartz is in the ppm range and not detected by the spectrometer.

Select from the following quartz NMR tubes:

S-5-600-QTZ-7 for 600 MHz 7” long
S-5-600-QTZ-8 for 600 MHz 8” long
S-5-500-QTZ-7 for 500 MHz 7” long
S-5-500-QTZ-8 for 500 MHz 8” long

Neglecting the area lost to the bottom curved portion of the tube, use the general formula: Volume = area of circle * height = πr2h

For a 5mm OD tube, the volume is 3.1416 X (0.42 cm/2)2 X 5.0 cm. Ans. 0.69 ml (1ml = 1cm3)

The Norell Select Series™ NMR tubes can be used in temperatures from -70 deg C to +200 deg C. We recommend the Standard Series™ tubes only for ambient temperature use.

Both of these types of NMR tubes are used for protecting samples from atmospheric gases. The Norell VT NMR tube offers greater sealing ability under vacuum and pressure applications. The screw cap tube should only be used to seal samples under ambient pressure and temperature conditions. We recommend either the following:

Norell VT item numbers:

S-5-600-VT-7 600 MHz 7” long
S-5-600-VT-8 600 MHz 8” long
S-5-500-VT-7 500 MHz 7” long
S-5-500-VT-8 500 MHz 8” long
S-5-400-VT-7 400 MHz 7” long
S-5-400-VT-8 400 MHz 8” long
S-5-300-VT-7 300 MHz 7” long
S-5-300-VT-8 300 MHz 8” long

Or the Norell Screw Cap item numbers:

S-5-600-SC-7 600 MHz 7” long
S-5-600-SC-8 600 MHz 8” long
S-5-500-SC-7 500 MHz 7” long
S-5-500-SC-8 500 MHz 8” long
S-5-400-SC-7 400 MHz 7” long
S-5-400-SC-8 400 MHz 8” long
S-5-300-SC-7 300 MHz 7” long
S-5-300-SC-8 300 MHz 8” long

Yes. Damage to the probe can occur when contact is made between the NMR tube and the probe's radio frequency coil. This can lead to receiver/transmitter de-tuning, resulting in a loss of signal power. Using Norell NMR tubes in all of your work will prevent damage to your rf coil and insert, because our quality manufacturing standards keep the outside tube dimensions and tube camber and concentricity values to extreme levels of precision from tube to tube.