Temperature inside vacuum

[Sunjay]

Dear All,

The Question is not related to Chromatography, sorry for that.

We generally perform Loss On Drying test under vacuum at 60°C (or higher). I would like to know what happens to temperature under vacuum?

Whether it increases or remains same?

Regards

[Alex Buske]

At a first assumption temperature is independend on pressure. What kind of vacuum your are talking about?

[HW Mueller]

As long as you evaporate something you consume energy of evaporation. The system will provide this energy and cool down if not heated.

[Uwe Neue]

Interesting question! Temperature is temperature, but the real question is how you transfer the desired temperature to your vial in vacuum. In air, it may happen from the air temperature and the temperature of the rack, on which your vial sits. In vacuum, you only rely on your rack. If you put the vial on a Styrofoam plate, it will never be at the desired temperature in the vacuum.

[Sunjay]

Dear All,

It is a procedure as generally specified in USP for doing Loss on Drying test by using Vacuum Drying Ovens . Generally one gram sample is taken in a LOD bottle, temp is set on the Oven (as mentioned in LOD procedure) and vacuum is applied. After specified interval LOD bottle is cooled and weighed.

Regards

[Peter Apps]

The sample should heat by radiation from the wall of the oven. I would be more comfortable "drying" to constant weight rather thanfor a specified time.

Peter