Studies of Ternary Complexes of Zn (II) Involving Aminocarboxylic Acids and NTA (Nitrilotriacetic Acid) by Paper Electrophoresis

Paper Electrophoresis study of mixed complexes of metal ions with 2-aminobenzoic acid, 3-aminobenzoic acid and 4-aminobenzoic acid as primary ligand and NTA as secondary ligand. Experimental procedure adopted for simple complexation studies is modified. The background electrolyte contains primary ligand in addition to perchloric acid and the pH is maintained at 8.5, the concentration of secondary ligand NTA is progressively increased and the electrophoretic observation of the metal ion spot on paper strip is taken at every addition of the secondary ligand, all the observations have been recorded under the Potential, 200 volts; Time, 30 min; Temperature, 25°C; Ionic strength, 0.1; Potential gradient; 6.66 volt/cm. Using the principle of average mobility, stability constant can be calculated with the help of mobilities .The higher values or stability constant of ternary complexes of 3-aminobenzoic acid than those of 4-aminobenzoic acid and 2-aminobenzoic acid and that of 4-aminobenzoic acid than 2-aminobenzoic acid are attributed to the stronger acidic character of 3-aminobenzoic acid than 4-amino, and 2-aminobenzoic acid and that of 4-aminobenzoic acid than 2-aminobenzoic acid. It must be noted that higher values of stability constants in case of ternary complexes than binary complexes indicate their increased stability.