The coupling of an infrared camera to a freeze dryer for monitoring of temperature of a pharmaceutical formulation (sucrose / mannitol solution, 4:1 %, m/m) during freeze-drying has been exploited further. The new development allows monitoring of temperature simultaneously at the surface as well as vertically (e.g. in depth) along the side using custom-made cuvettes. The IR-camera was placed on the chamber-roof of a process-scale freeze dryer. Monitoring of cuvettes containing the formulation took place from above where one side of each cuvette was equipped with a germanium window. The Ge-window was placed next to an IR-mirror having a 45° angle. The infrared radiation coming from the inside of the cuvette was reflected upwards towards the IR-camera. Accurate recording of the temperature along the cuvettes’ depth profile was therefore possible. Direct imaging from - 40 °C to 30 °C took place every 60 s on the surface and on the side with a 2 x 2 mm resolution per IR-pixel for 45 h resulting in 2700 thermograms. Results are presented for freeze-drying of the pharmaceutical formulation as a function of time and spatially for the entire side (depth) of the cuvette. As the sublimation process was progressing, the spatial resolution (84 IR-pixels for the side-view and 64 pixels for the surface-view) was more than sufficient to reveal lower temperatures deeper down in the material in contrast to the surface.

EMTEBORG Hakan;  CHAROUD-GOT Jean;  SEGHERS John; 

2022-11-28

MDPI

JRC128977

1999-4923 (online),   

https://www.mdpi.com/1999-4923/14/5/1007,    https://publications.jrc.ec.europa.eu/repository/handle/JRC128977,   

10.3390/pharmaceutics14051007 (online),