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High-pressure Sapphire Cell for Phase Equilibria Measurements of CO2/Organic/Water Systems
Published on: January 24, 2014
A refined phase diagram of the tert-butanol-water system and implications on lyophilization process optimization of
Bakul S Bhatnagar1, Jayesh Sonje1, Evgenyi Shalaev2
1Department of Pharmaceutics, College of Pharmacy, 308 Harvard St. SE, University of Minnesota, Minneapolis, MN 55455, USA. surya001@umn.edu.
Abstract:
While water is the solvent of choice for the lyophilization of pharmaceuticals, tert-butyl alcohol (TBA) along with water can confer several advantages including increased solubility of hydrophobic drugs, decreased drying time, improved product stability and reconstitution characteristics. The goal of this work was to generate the phase diagram and determine the eutectic temperature and composition in the "water rich" region (0.0 to 25.0% w/w TBA) of TBA-water mixtures. Solutions of different compositions were frozen and characterized by low temperature differential scanning calorimetry and powder X-ray diffractometry (XRD). The thermal events observed during warming, and their characterization by XRD, enabled the generation of phase boundaries as well as the eutectic temperature and composition. While TBA crystallized as a dihydrate in frozen solutions, on heating, the dihydrate transformed to a heptahydrate. TBA heptahydrate and ice (22.5% w/w TBA) formed a eutectic at ∼-8 °C.
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