PT  - JOURNAL ARTICLE
AU  - Jennings, Thomas A.
TI  - Discussion of Primary Drying during Lyophilization
DP  - 1988 Jul 01
TA  - PDA Journal of Pharmaceutical Science and Technology
PG  - 118--121
VI  - 42
IP  - 4
4099  - http://journal.pda.org/content/42/4/118.short
4100  - http://journal.pda.org/content/42/4/118.full
SO  - PDA J Pharm Sci Technol1988 Jul 01; 42
AB  - This paper examines, by means of an ideal model, the controlling mechanisms invoiced in the primary drying of the lyophilization process. With the aid of the model, the effect of temperature and desorption energy on the fraction of water molecules on the surface of the “disorder” layer, at any one instant, that have sufficient energy to leave the surface is examined. It is shown that the effect of an increase in chamber pressure, while maintaining the shelf-surface temperature, is to cause an increase in the product temperature which results in a decrease in the unit sublimation rate. Experimental data is presented to show that a significant sublimation rate can only occur when chamber pressure falls below the initial vapor pressure of the ice. The sublimation rate is shown to be best estimated from a knowledge of the heat flux (q) and the heal of sublimation.