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Using Differential Scanning Calorimetry (DSC) for Optimized Lyophilization Cycle Design
ABSTRACT:
By understanding the physio-thermal characteristics of the product to be freeze dried and designing the lyophilization cycle around these properties, the scientist can ensure that the product will be dried in the shortest time possible while still maintaining the desired quality and cosmetic attributes.
This paper describes how to interpret the results of a Digital Scanning Calorimeter (DSC) to determine the critical temperature (glass transition temperature, eutectic melting temperature or collapse temperature) of a frozen product, which is the warmest temperature that the product can be exposed to without collapse. Also explained is how to determine whether the frozen state of the product is either crystalline, amorphous or metastable, and if an appropriate thermal treatment (annealing) step should be included in the freezing portion of the lyophilization cycle. Examples of typical DSC outputs are provided and the typical endotherms associated with each frozen state are identified.
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