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- NMR training is mandatory for users who want to run experiments on any of the five spectrometers.
- Users who have completed NMR training will gain access to the NMR lab where the corresponding spectrometers are located.
- Users with no previous NMR experience should complete training for AVIII 400/500 first.
Frequently Asked Questions
1. What are the sensitivity differences among the 400, 500, 600_QNP and 600_QCI?
When the 1H NMR sensitivity for AVIII400 is normalized to 100, the sensitivities for AVIII500, AVII600_QNP and AVIII600_QCI are 269, 529 and 652, respectively. Similarly, after the 13C sensitivity (with 1H decoupling) for AVIII400 is normalized to 100, the sensitivities for AVIII500, AVII600_QNP and AVIII600_QCI are 70, 357 and 420, respectively. NMR users should be aware that the sensitivity differences result mainly from the magnetic field strength and the probe installed.
2. How much sample is needed for an NMR experiment?
As a rough guidance for experiments on AVIII400, for 10mg of sample (MW<=500), the following experiments should produce spectra with reasonably good quality: 1H (16 scans); 13C (~60min); 1H COSY (~10min); 1H-13C HSQC(~20min); 1H-13C HMBC(~60min); 1H NOESY (~60 min);
Using the above sensitivity ratios, the time needed for getting a spectrum with same quality on other spectrometers can be estimated.
3. Which spectrometer should I use?
For 1H NMR, if the amount of the NMR sample is not very limited, e.g. greater than 5mg, any of the four spectrometers will be ok. When the mass is far less than 5mg, using the 600s is suggested. For 13C and 2D NMR, if a single experiment will likely take longer than 3~4 hours, the user is suggested to use the 600_QNP/600_QCI.
The user should be aware that the 500 has much better 1H sensitivity than the 400, which can significantly reduce time for 1H detected 2D NMR (COSY, NOESY, HSQC, HMBC, etc.) On the other hand, the 500 has lower 13C sensitivity than the 400, which will result in longer time to acquire a 13C spectrum with same quality on the 500. When the highest sensitivity is needed, the users can use either 600_QNP or 600_QCI, although the latter has slightly better sensitivity in both 1H and 13C NMR.
4. How can I run variable temperature NMR?
Technically, all of our spectrometers have the capability of VT NMR. Nevertheless, since the 400 and the 500 run experiments via automation mode, which means full of samples most of time, and the 600s have limited temperature ranges due to cryoprobes, the most suitable spectrometer for VT is the 400_solids which can be switched for solution NMR. NMR users can submit samples to us for VT experiments, or run by themselves after completion of VT NMR training.