Differential Pulse Polarography was used to study the complexation of Ni(II) and Zn(II) with Salicylaldoxime in highly dilute solutions. The stability constants for both Ni(II) and Zn(II) complexes were calculated for three different metal to ligand concentration ratios viz 1:10, 1:50 and 1:100, from the shift in peak potential. The Log Kf values were found to be 9.39, 9.49 and 9.49 for Ni(II) complex and 8.82,8.28 and 8.89 for Zn(II) complex in 10, 50 and 100 times concentrated solution of Salicylaldoxime respectively. For ten and fifty times concentrated solution of Salicylaldoxime, the complex formation was stepwise while for hundred times concentrated solution of Salicylaldoxime, the complex formation was found to be a single step process. The molar combining ratio of metal to ligand was found to be 1:2 for both Ni(II) as well as Zn(II).
Keywords : Salicylaldoxime, Differential pulse polarography, stability constant, concentration ratio, peak potential.