Bruker NMR User Manual

Advanced Operation
24 Z33085_2_002
The best performance (with low concentrations of the thermometer substance) can be
expected using cryogenically cooled probes at high magnetic field strengths (600 MHz and
higher), because the
2
H sensitivity will be the highest. Therefore, check the
2
H sensitivity of
your system beforehand. Nevertheless, the NMR Thermometer also works at lower fields
(e.g. 400 MHz) with room temperature probes.
The
2
H sensitivity of a room temperature probe, such as an inverse or broad band observe
probe, is about a factor 5-10 times lower compared to a cryogenically cooled probe. The
concentration of the NMR Thermometer compound therefore needs to be higher, as listed in
the following table:
Figure 5.8: Typical concentrations required for the NMR Thermometer compound. If the NMR
Thermometer compound is used with pure D2O as solvent, the higher concentration of the thermometer
compound is required due to the high dynamic range of the intensity of both lock compounds.
Considerations for Shimming with Topshim
Depending on the solvent, topshim will use
1
H or
2
H as a shim nucleus. For aqueous
solutions, e.g. 5% D
2
O in H
2
O,
1
H is the shim nucleus, therefore the shim routine for Topshim
does not need to be changed. For deuterated organic solvents
2
H is used as the shim
nucleus. If the solvent contains more than one
2
H signal, like methanol-d
4
and pyridine-d
5
,
Topshim will use a selective
2
H pulse in order not to excite additional signals.
In the case where the thermometer compound is used together with an organic solvent, either
in a mixture with the solvent or as an external capillary, the shim routine has to be adapted. In
the following the procedure for the setup of the shimming routine for a new solvent is
described.
Two steps should be performed:
• Define a new solvent with edlock. The procedure is described in the section Define a New
Solvent [} 19] of this manual.
• Define the shimming routine for Topshim.
The command for defining the Topshim shim parameters is:
topshim solvcal solvent= <new solvent name as in edlock> where <new solvent name as
in edlock> is exactly the name of the solvent as defined in the lock/solvent table.
The following example will show the setup for a solvent called New.
1. Enter the command topshim solvcal solvent=New. A window pops up allowing the
selection of a solvent. Here it is of no importance which solvent is selected:
5.2.3

Bruker NMR Specifications

General

Brand	Bruker
Model	NMR
Category	Thermometer
Language	English