3.6. Evaluation of the Primary Drying Time

A thermal camera (FLIR A655sc IR camera, Thermal Focus, Ravels, Belgium) was used to monitor the vial temperature during primary drying through a germanium window. Van Bockstal et al. [23] described that a steep increase in vial temperature is a good marker for the end of primary drying. The primary drying time was determined for each formulation and each freezing-rate.