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Advanced Operation
22 Z33085_2_002
For the selection of a suitable compound the following points should be considered:
• Large number of deuterons: The larger the number of chemically equivalent deuterons,
the lower the required concentration. Tetramethylammonium chloride-d
12
is in this respect,
the preferred compound, whereas sodium acetate is less favorable.
• Possibly one additional 2 H signal.
• Moderate or no salt effect: Salts and acids in aqueous solution will increase the
conductivity of the sample, which might cause a loss of sensitivity and an increase of the
pulse length.
• The compound should not interact with the sample or change essential structural
properties of the sample.
• Acceptance. Difference compounds are commonly added to protein solutions. These can
be buffers like TRIS or stabilizers like EDTA. These compounds can be used if deuterated
and available at a sufficiently high concentration.
• Price and availability.
Predefined Solvents for the NMR Thermometer
The lock table contains solvents which are setup for usage with the NMR Thermometer. For
these solvents a temperature calibration of the chemical shift difference of the two
2 H signals
has been performed and is included. These are the following solvents:
T_MeOD: methanol-d
4
T_H2O+D2O+NaAc: sodiumacetate-d
3
in 90% H
2
O, 10% D
2
O
T_H2O+D2O+Me4NCl: tetramethylammoniumchlorid-d
12
in 90%, H
2
O, 10% D
2
O
T_H2O+D2O+Pivalate: pivalic acid-d9 sodium salt in 90%, H
2
O, 10% D
2
O
Depending on the probe, the lock power may need to be adjusted.
5.2.1