RAPID AND SIMULTANEOUS DETERMINATION OF COPPER, CADMIUM, NICKEL, AND COBALT IN ZINC ELECTROLYTE SOLUTIONS BY COMPLEX ADSORPTION WAVE POLAROGRAPHY

ABSTRACT Complex adsorption waves of Cu(II), Cd(II), Ni(II) and Co(II) in substrate solution (pH = 9.0) of diacetyldioxime–ammonia–ammonium chloride–sodium citrate–gelatin–ascorbic acid were studied and a new method for determination of trace amounts of Cu, Cd, Ni and Co in aqueous solutions was developed. The results show that there are sensitive complex adsorption waves of Cu(II), Cd(II), Ni(II) and Co(II) complexes at about −0.44, −0.76, −1.07 and −1.24 V, respectively. The method is easy to operate and able to determine Cu, Cd, Ni and Co in aqueous solutions rapidly and simultaneously, and when the signal-to-noise rates equal 3, the detection limits of copper, cadmium, nickel and cobalt are 1.0 × 10−8, 1.3 × 10−8, 2.9 × 10−10 and 3.6 × 10−11 mol/dm3. Good linear relationships exist between the concentrations and the current peaks when those of copper, cadmium, nickel and cobalt are within 2.0 × 10−8 ∼ 10−5, 3.0 × 10−8 ∼ 10−5, 5.4 × 10−10 ∼ 10−7 and 6.8 × 10−11 ∼ 10−8 mol/dm3, respectively. The method has been used in the rapid and simultaneous determination of these metal ions in complex zinc electrolyte solutions with satisfactory results.