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Sublimation of formaldehyde in freeze-drying
Developments in Biological Standardization
|October 1, 1976
Summary
Formaldehyde, used in vaccine preparation, can harm antigens during freeze-drying. Adding methanol prevents formaldehyde polymerization and enhances its sublimation, improving vaccine antigen stability.
Area of Science:
- Biotechnology
- Vaccine Development
- Analytical Chemistry
Background:
- Formaldehyde solution is a common inactivating agent for microbial and viral suspensions in vaccine production.
- Formaldehyde can negatively impact antigen integrity during freeze-drying (lyophilization).
Purpose of the Study:
- To investigate the behavior of formaldehyde during the freeze-drying process.
- To evaluate methods for mitigating formaldehyde's detrimental effects on antigens during lyophilization.
Main Methods:
- Formaldehyde sublimation was monitored in shell-frozen and plug-frozen aqueous samples during freeze-drying.
- Residual formaldehyde levels were measured periodically.
- The effect of methanol addition on formaldehyde sublimation and polymerization was assessed.
Main Results:
- Formaldehyde concentrated volumetrically during sublimation, particularly in plug-frozen samples.
- Formaldehyde polymerized into paraformaldehyde in samples dried to completion.
- Methanol addition prevented paraformaldehyde formation and increased formaldehyde sublimation without concentration.
Conclusions:
- Formaldehyde's behavior during freeze-drying poses risks to vaccine antigen stability.
- Methanol is a potential additive to improve formaldehyde removal and prevent antigen damage during lyophilization.