Temperature ramping, secondary drying

While lyophilizing ampoules on trays under maximum vacuum, we have effectively observed a prolongation of primary drying by 20-30% under partial load conditions. However, in no case was an increase in product temperature noticeable, even when the transition ramp to secondary drying was started before completion of product primary drying. 

Figure 5 Sketch of a practical secondary drying process, based on a stepwise temperature ramping, interspersed with thermal equilibration periods, between the limits of Tg and T. The process aims at a combination of economy of time with acceptable product quality and is based on the extension of the ideal" drying protocol, shown in Figure 5...

An overdrying secondary drying with a ramped shelf temperature of 25°C and a chamber pressure of lOOmTorr for a total of 24h. 

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