Stability Constant of Vanadium (IV) with Alanine at Different Ionic Strength

The stability constant on complexation of VO2+ with alanine has been determined by a combination of spectrophotometric and potentiometric methods at (25 ± 0.1)ºC and various ionic strengths in the range (0.1 to 0.8) moldm-3 (sodium perchlorate) in the pH range 1.3-2.8 with high ligand-to-metal ratios. In this study an equilibrium model, MY, is assumed, where M and Y represent the metal ion and fully dissociated amino acid anion, respectively. Also, the results are discussed in terms of the dependences of protonation and complexation on ionic strength by a Hückel type equation.