Gallium (III)-acetate speciation studies under physiological conditions.

This paper describes an experimental investigation in aqueous solution of the equilibria between gallium (III) metal ions and acetate ions as a model of low-molecular-weight ligand using potentiometric techniques under physiological conditions of temperature 37 °C and ionic strength 0.15 mol.dm-3 NaCl. Potentiometric measurements were monitored with the help of a glass electrode calibrated daily in hydrogen ions concentrations. Several metal to ligand ratios were used and the respective titrations data obtained in the pH range of 2.3-5.3 were treated using the SUPERQUAD computer program to determine global stability constants. Different species were considered during the calculation procedure and the following hydroxides have been characterized: , and coexist with one mononuclear complex Ga(CH3COO)+2. Speciation calculations based on the determined constants were then used to simulate the species distribution as a function of pH