Equipment Capability Measurement of Laboratory Freeze-Dryers: a Comparison of Two Methods

The objective of this investigation was to evaluate two methods for measuring the maximum sublimation rate that a freeze-dryer will support—the minimum controllable pressure method and the choke point method. Both methods gave equivalent results, but the minimum controllable pressure method is prefe...

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Bibliographic Details
Published in:AAPS PharmSciTech 2021-01, Vol.22 (1), p.53-53, Article 53
Main Authors: Srinivasan, Jayasree M., Sacha, Gregory A., Kshirsagar, Vaibhav, Alexeenko, Alina, Nail, Steven L.
Format: Article
Language:English
Subjects:
Biochemistry
Biomedical and Life Sciences
Biomedicine
Biotechnology
Freeze Drying - instrumentation
Pharmacology/Toxicology
Pharmacy
Pressure
Research Article
Spectrum Analysis
Temperature
Water - chemistry
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Summary:The objective of this investigation was to evaluate two methods for measuring the maximum sublimation rate that a freeze-dryer will support—the minimum controllable pressure method and the choke point method. Both methods gave equivalent results, but the minimum controllable pressure method is preferred, since it is easier, faster, and less subjective. The ratio of chamber pressure to condenser pressure corresponding to the onset of choked flow was considerably higher in this investigation (up to about 20:1) than in previously published reports. This ratio was not affected by the location of the pressure gauge on the condenser; that is, on the foreline of the vacuum pump versus on the body of the condenser itself. The total water loss due to sublimation as measured by tunable diode laser absorption spectroscopy was consistently within 5% of gravimetrically determined weight loss, regardless of whether the measurement took place during choked versus non-choked process conditions.
ISSN:1530-9932
1530-9932
DOI:10.1208/s12249-021-01921-2