Potentiometric studies of the complexes formed by copper (II) and zinc (II) with some polar uncharged amino acids

Abstract

The overall stability constants of copper (II) and zinc (II) ions with some polar uncharged amino acids including proline, threonine and asparagines were determined by potentiometric titration in aqueous solution. The values of the constants were found using ORIGIN 50 program computational method of analysis to be 19.56, 20.32, and 17.87 for copper (II) prolinate, copper (II) threoninate and copper (II) asparaginate respectively, that of zinc (II) prolinate, zinc (II) threoninate and zinc (II) asparaginate were found to be 18.51, 18.69 and 16.98 respectively. The average number of coordinated amino acids to the copper (II) and zinc (II) ions were found to be two in all the complexes.

Keywords: Copper(II) ion, Potentiometric, Stability constant, Zinc(II) ion.