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Applications
Z33085_2_002 27
Applications
Identical Chemical Shifts at Different Spectrometers
One of the most important applications of the NMR Thermometer is to use it as internal
temperature reference and correct the temperature offset between sample and the
temperature sensor of the probe. This is in general comparable to the conventional
temperature correction (described elsewhere) using the methanol sample (or other
temperature calibration samples) derived from two
1 H spectra measured at two different
temperatures.
In the case of the NMR Thermometer you just insert the methanol sample (99.8% deuterated)
and after setting up the system (tuning/matching/shimming) the sample temperature is
displayed immediately. After enabling the NMR Thermometer the sample temperature can be
used as target temperature (edte). If the temperature is stable the sample is replaced by, for
example, 2 mM sucrose sample in 9:1 H
2
O/D
2
O and a 1 H spectrum is acquired. Repeating
the same procedure at a second spectrometer leads to a very small shift difference
corresponding to a temperature difference of about 40 mK:
Figure 6.1: Overlay of a 1H spectrum of 2 mM sucrose (standard sample) measured at 600 MHz (TXI
probe) and 800 MHz (TCI CryoProbe).
Changing the sample to a 0.5 mM ubiquitin sample in 9:1 H
2
O/D
2
O (figure below) nicely
shows the precision of the temperature correction obtained by the NMR Thermometer using
the methanol sample (99.8% deuterated) as temperature reference.
6
6.1