Phase separation and thermodynamics of the mixture of metformin hydrochloride + triton X-100 in ammonium salts media: impacts of composition of media

Abstract

Cloud point (CP)/lower consolute temperature (LCT) of aqueous mixture of TX-100 and a highly recognised anti-diabetic drug metformin hydrochloride (MNH) was analysed in absence/presence of NH₄Cl, NH₄NO₃, (NH₄)₂SO₄ and (NH₄)₂HPO₄. The CP values were found to be decreased with increasing concentrations of ammonium salts. Occurrence of aggregation in respective solution systems might result in declining of corresponding CP. Thermodynamic parameters ($\mathrm{\Delta }{G}_c^0$, $\mathrm{\Delta }{H}_c^0$ and $\mathrm{\Delta }{S}_c^0$) were calculated at CP. The appearance of positive values of Gibbs free energy ($\mathrm{\Delta }{G}_c^0$) indicates that clouding in the studied system was thermodynamically non-spontaneous and the degree of non-spontaneity was diminished with increasing in the extents of electrolytes. The computed enthalpy ($\mathrm{\Delta }{H}_c^0$) and entropy ($\mathrm{\Delta }{S}_c^0$) values of the system showed negative values in cases of aq. NH₄Cl, (NH₄)₂SO₄ and (NH₄)₂HPO₄ while the negative values tend to reduce with rise of electrolytes content. In case of aq. NH₄NO₃ medium, the reverse results for the $\mathrm{\Delta }{H}_c^0$ and $\mathrm{\Delta }{S}_c^0$ values were detected. The $\mathrm{\Delta }{H}_c^0$ and $\mathrm{\Delta }{S}_c^0$ values in the studied system indicate the presence of electrostatic interaction between TX-100 and MNH in NH₄Cl, (NH₄)₂SO₄, (NH₄)₂HPO₄ media whereas the hydrophobic interactivity might play a great role within the mixture when it was placed in the NH₄NO₃ solution.

GRAPHICAL ABSTRACT

KEYWORDS:

• Metformin hydrochloride
• TX-100
• ammonium salts
• CP
• intrinsic enthalpy gain

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Authors are grateful to the Researchers Supporting Project number (RSP-2021/393), King Saud University, Riyadh, Saudi Arabia.