Abstract:

pH changes during freezing played a critical role in maintaining the biostabilization of biomacromolecules after lyophilization. In this study a mathematics model based on the Mazur equation was applied to explore pH changes during freezing. The pH change with temperature and time during freezing was simulated for different buffer systems. Fluorescence images under different conditions were taken using a fluorescence microscopy during freezing. pH was determined using an image analysis method. The simulation results revealed that the pH value of the system during freezing can be predicted using the mathematic model. The non-invasive method developed is able to measure the system pH during freezing.

Key words: freeze-drying; non-invasive approach; pH change equation