Hello, how much benefit in resolution and signal-to-noise will we get when using 800 MHz rated tubes (on the 800 MHz instrument) vs
Is it worth spending the extra money on ultra-high quality tubes for routine work at 800 MHz?
asked Aug 13 '10 at 14:07
Most laboratories that have an 800 Mhz NMR spectrometer, usually also have several lower field NMR spectrometers to be used for 'routine' work. The higher field spectrometers are usually used only when the higher resolution and sensitivity is required.
In general the cost of the NMR tubes is very small compared to the cost of the NMR instrument (unless the instrument is being used in a high throughput mode), and the costs involved in the preparation of the sample. Hence, in most cases it is worthwhile to use tubes rated for the appropriate instrument - the only exception is when resolution of the NMR experiment is not important and the higher field is only being used to obtain higher sensitivity. e.g. NMR experiments of large biomolecules in 100% D2O without sample spinning. If sample spinning is used, then a mismatch between the specifications of the NMR tube and probe may lead to breakage of tube within the probe - this would lead not only to sample loss but also cause damage to the probes.
The line widths of proteins and other biomolecules are broad, therefore a small a change in resolution does not affect the observed peaks - HOWEVER, most bioNMR experiments are performed in water and the quality of water suppression would be affected significantly by the quality of the tube.
If the NMR spectrometer is used in high throughput mode (e.g. for screening), then the costs of the NMR tubes may be significant because of the large number of NMR tubes used and may indeed exceed the cost of the sample. As I have no practical experience with such cases, I can make no recommendation regarding the NMR tubes to be used for high throughput applications. My guess is that you could use 500 MHz rated tubes (assuming that the 500 MHz rated tubes have the same specifications with regard to inner and outer diameters as those of 800 MHz rated tubes, but have less precise control over camber than the 800 Mhz tubes) if the samples are not subjected to spinning. The earlier generations of robots used in automated samplers used to break NMR tubes quite frequently, leading to stoppage of workflow - this problem has almost certainly been resolved in the newer generation of robots - but I would not be surprised if the frequency of such accidents is related to the specifications of the NMR tubes.
I recomend vizit Norell site (nmrtubes.com) Technical Information part. Very intresting FAQ. More detailed information collected in their Catalog. The difference between 500MHz and 800MHz tubes(especially camber parameter) near 5 times. Moreover even in same party will find a hard shimming tube. In my opinon, a tube should correspond to assigned task, BUT 90% of "benefit" will depend on preparation of sample (degassing, filtering, etc).
answered Sep 04 '10 at 01:32