Development of Drying Process for Removal of Residual Solvent from Crystalline Vancomycin and Kinetic and Thermodynamic Analysis Thereof

Abstract

In this study, a drying method using ethanol pretreatment was developed that can effectively remove residual solvent from crystalline vancomycin. Microwave-assisted drying with ethanol pretreatment was sufficient to remove residual acetone and ethanol concentrations below the ICH limits (5,000 ppm for acetone and 5,000 ppm for ethanol). At all the microwave power (100, 200, 300 W), a large amount of the residual acetone was initially removed during the drying, and the drying efficiency increased when increasing the microwave power. In addition, the drying kinetics and thermodynamics were examined. The experimental data were fitted to the Newton, Page, Modified Page, Henderson and Pabis, and Geometric models. Comparison of results revealed that the Page model was the most appropriate. The activation energy of microwave-assisted drying was found to be 10.8792 kJ/mol. The Standard Gibbs free energy change was determined to be negative, while the standard enthalpy change and entropy change were positive. These results revealed the endothermic, irreversible and spontaneous nature of drying.