PT  - JOURNAL ARTICLE
AU  - Thomas A. Jennings
TI  - The Effect of Resistivity Probe Design on the Measurement of the Freezing Temperature of Lyophilized Formulations
DP  - 1980 Mar 01
TA  - PDA Journal of Pharmaceutical Science and Technology
PG  - 109--126
VI  - 34
IP  - 2
4099  - http://journal.pda.org/content/34/2/109.short
4100  - http://journal.pda.org/content/34/2/109.full
SO  - PDA J Pharm Sci Technol1980 Mar 01; 34
AB  - The primary phase of the vacuum freeze drying process is based on the freezing temperature of the material. This paper considers the effect that the design and construction of resistivity cells will have on the determination of the freezing temperature. The nature of the electronics measuring circuit and each of the three basic cell designs will be described. A mathematical model will be used to depict the resistivity of an iceproduct matrix. The resistivity, as a function of temperature, will be presented for distilled water, a 2½% potassium chloride solution, a 2½% mannitol solution, and a combined solution of potassium chloride and mannitol. Based on a mathematical model and the experimental results, a discussion will be made as to the effect resistivity cell design will have on determining the freezing temperature of a product.