Freeze-drying of a solution consists in first crystallizing it totally, then sublimating the formed ice on installing vacuum. In order to obtain a final product of good quality, it is necessary to install vacuum at a temperature lower than the glass temperature (Tg) of the frozen solution.
Instrument : micro-DSC VII
Sample : 365 mg of solution
The temperature is programmed from -32°C to -40°C at 0.09 K.min-1 : 5.4 K.h-1.
The DSC curve presents a Tg with an inflexion point at -37.85°C.