Volumetric and aggregation properties of metformin hydrochloride in methanol in temperature range of (288.15–318.15) K

Abstract

This manuscript is related to the study of volumetric and micellar properties of metformin hydrochloride (Met-HCl) in methanol in temperature range of (288.15–318.15) K. Conductometric and refractive index data was used to find CMC of drug. From conductometric data various thermodynamic variables were calculated which include free energy of micellization, entropy of micellization and enthalpy of micellization. Density measurements of different drug solutions at specified temperatures were utilized for the calculation of apparent molar volume, partial molar volume, Hepler's constant and partial molar expansivity. These parameters are important for getting an understanding about different types of interaction of drug in solution. Met-HCl showed strong solvophobic than electrostatic interaction with methanol and had a structure promoting effect on it which was apparent from positive value of partial molar volume, Hepler's constant and partial molar expansivity. Micellization process was spontaneous, endothermic and resulted in increase in entropy of system because Gibbs energy change was negative, enthalpy change and entropy changes were positive.