Analytical investigation of solubility and solid-state transformation of Amikacin sulphate in magnetized water compared with organic solvents

The present work investigates the solubility of amikacin sulphate in five solvents, namely magnetized water, distilled water, methanol, ethanol, and propanol, over a range of temperatures of ۲۹۸.۱۵-۳۲۸.۱۵ K. To perform the measurements, the gravimetric method was used. The results showed an apparent solvent-dependent behaviour. Magnetized water consistently exhibited the highest solubility of amikacin sulphate among the tested temperatures. At ۳۲۸.۱۵ K, the mole fraction solubility in magnetized water reached ۳۳.۹۴۵ ×۱۰⁻³, whereas it was ۲۱.۲۵۸ ×۱۰⁻³ and ۱۱.۸۶۶ ×۱۰⁻³ in distilled water and propanol, respectively. The findings were acceptable using both the modified Apelblat equation (R² = ۰.۹۹۴۶۸) and the Van’t Hoff model, enabling the extraction of thermodynamic parameters. Moreover, the dissolution in magnetized water was characterized by a negative Gibbs free energy (ΔG= –۵۱.۳۰۱ kJ mol-۱) and a high positive entropy change (ΔS = ۶۵.۵۸۸ J/mol. K). This will suggest a spontaneous and entropy-driven process. Additionally, scanning electron microscopy (SEM) images showed a reduction in particle size to ۱۶.۲۹-۳۰.۹۱ nm at ۲۵ °C in magnetized water, and to ۱۸.۱۰-۲۶.۴۵ nm at ۵۵ °C. The tests of X-ray diffraction (XRD), Thermogravimetric analysis and Differential Scanning Calorimetry (TGA and DSC) further confirmed an improved amorphous character with enhanced thermal stability. These findings clearly indicate that magnetized water is a highly effective medium for dissolving amikacin sulphate. This could motivate research into the implications of magnetized water for improving bioavailability in pharmaceutical formulations.

Keywords:

analytical method , Amikacin sulphate , Magnetized water , Thermodynamics , Solubility , Correlation