Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

Abstract

Densities $(\rho )$ of (0.01 to 0.07) $\hbox {mol}{\cdot } \hbox {kg}^{-1}$ L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) $\hbox {mol}{\cdot } \hbox {kg}^{-1}$ solutions have been reported as a function of temperature at $T = (298.15, 303.15, 308.15$, and 313.15) K and atmospheric pressure. The accurate density $(\rho )$ values are used to estimate the various parameters such as the apparent molar volume $(V_{2,{\upphi }})$, the partial molar volume $(V_{2}^{\infty })$, the isobaric thermal expansion coefficient $(\alpha _{2})$, the partial molar expansion $(E_{2}^{\infty })$, and Hepler’s constant $(\partial ^{2}V_{2}^{\infty }/\partial T^{2})_{P}$. The Cosphere overlap model is used to understand the solute–solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler’s constant $(\partial ^{2}V_{2}^{\infty }/\partial T^{2})_\mathrm{P}$ is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.