Probing the Interactions of Calcium Lactate with Glycine and <scp>l</scp> -Leucine in Water Using Volumetric Properties

The hydration behavior of glycine and L-leucine was examined in aqueous solutions of calcium lactate. The experiments were accomplished at atmospheric pressure across a temperature range from 293.15 to 318.15 K, emphasizing the nature of solute–solvent interactions. The volumetric properties were estimated by employing experimentally measured density and speed of sound results. The interactions between leucine or glycine and calcium lactate were analyzed by using the values of apparent molar volume, apparent molar isentropic compressibility, infinite dilution partial molar volume, and volume of transfer. The volumetric transfer parameters were determined and analyzed using the cosphere overlap model. Among all of the interactions present in the system, hydrophilic interactions were found to be the most dominant. These interactions were more pronounced in the case of glycine compared to leucine. The positive contribution to the volume may be attributed to the interaction between calcium ions and the carbonyl or amino groups of the amino acids. Additionally, the hydrophobic lactate group of calcium lactate may engage in hydrophobic interactions with the nonpolar regions of the amino acids in aqueous solution. However, the hydrophilic interactions significantly outweigh the hydrophobic contributions.