Potentiometric Investigations of Chromium (III) Amino Acid Complexes

Potentiometric investigations of complexes formed by chromium (III) ion and amino acids have been carried out. The dissociation constants of the amino acids, the stepwise formation constants and the overall stability constants of the metal ions and amino acids complexes were determined. The dissociation constants of the amino acids determined are; alanine (10.29), arginine (12.02), asparagine (9.39), glycine (9.87), histidine (7.01), lysine (9.28), methionine (9.68), phenyalanine (9.61), proline (10.53), threonine (10.31), tryptophan (9.77), and valine (10.28). The average number of coordinated amino acids to chromium (II) ion determined is 3. The Stepwise Stability Constants of chromium (III) ion and amino acid complexes determined have been found to decrease in the order K1 > K2 > K3 for all the complexes. The values of the overall stability constants of the complexes obtained are relatively high indicating good stability for the complexes.