Selective determination of Cu(II), Pd(II), Pb(II) and Cd(II) with N-phenyl-3- methyl-4-phenyl hydrazono pyrazolin- 5-one

Abstract

A method is proposed for the spectrophotometric determination of divalent Cu, Pd, Pb and Cd from nitric acid media after extraction of their complexes with N-phenyl-3-methyl-4-phenyl hydrazono pyrazolin-5-one [PMPHP] onto molten naphthalene. Dioxane, methanol, ethanol, acetone and acetonitrile are used as the organic component of the mixed (polar) phase. Maximum enhancement is obtained with acetonilrile. Beer's law is obeyed in the following concentration ranges: Cu, 5.0-110.0 µg; Pd, 10.0-90.0 µg; Pb, 6.0-90.0 µg; and Cd, 5.0-125.0 µg/10ml of the final solution. The molar absorptivities (dm³ mol^-I em^-I) and Sandell's sensitivities (l1g cm-2) are as follows: Cu(II)=0.89x10⁴ and .0071, Pd(II)=O.83xl 04and .0120, Pb(II)=2.1 Ox10⁴and .0098 and Cd(II)=1.52x10⁴ and .0074, respectively. Ten replicate analyses containing 20.0 µg of Cu(II), 40.0 µg of Pd(II), 36.0 µg of Pb(II) and 20.0 µg of Cd (II) give mean absorbances of 0.282, 0.310,0.365 and 0.270 with relative standard deviation of 0.53, 0.26, 0.95 and 1.05%, respectively. The interference of various ions has been studied. The method has been applied for the determination of these metals in some alloys.