VP-ITC MicroCalorimeter User’s Manual
3.2 Using the ThermoVac to Degas Samples
Degas cell and syringe samples that may contain dissolved gas to insure bubble free loading of
each. This is particularly important if samples recently were at refrigerator temperatures. A
ThermoVac sample degassing and Thermostat station is provided with each instrument. The
ThermoVac’s preset vacuum time of ca. 5 minutes is adequate to degas a sample that is being
stirred, but a much longer time is required without stirring. Normally, you would set the
ThermoVac temperature to 1 to 5 degrees below the intended experimental temperature while
degassing. If volatile buffers or ligands are being used then solutions should be prepared from
degassed or pre-boiled water and stored air-free. If sample solutions contain any undissolved
solutes or extraneous solid material of other types, they should be filtered before use.
Please note: When running experiments below ambient temperature, the temperature of the
sample should be such, that after loading into the cell, it is at or below the experimental
temperature. This will prevent a long equilibration period before the experiment can start (see
page 78 for more information). Therefore, if running an experiment much below room
temperature you may wish to set the ThermoVac temperature 5 degrees below the experimental
temperature, as the sample may warm up during the transfer to the calorimetric cells.
Additionally, the temperature of the filling syringe itself will act to change the sample
temperature during cell filling. For this reason users may consider using a cold syringe (stored in
a refrigerator) to minimize the sample temperature change during cell filling. The temperature of
the injection syringe sample has little effect on the equilibration period.
Top View of ThermoVac
Note:
The ThermoVac includes a preinstalled bleeder valve on the top of the vacuum cap to
allow manual adjustment of the vacuum strength in the degassing chamber. If the vacuum is
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