SPECTROPHOTOMETRIC DETERMINATION OF ZINC(II) AND COPPER(II) IONS

Abstract

An organic analytical reagent - monosodium salt of 5-methyl- (pyridyl-2-azo) -1,8-aminonaphthol-2,4-disulfonic acid (HR, 5MPAANS.S-2.4) was synthesized and the IR spectrum studied and molar absorption coefficient (ε=3306) and the dissociation constant (K_dis=2.95∙10^-8 (pK=7.53)) were determined and quantum-chemical calculations. Were carried out the qualitative reactions of 5MPAANS.S-2.4 with metall ions: Сu(II), Zn(II), Hg(II), Co(II), Cd(II), TI(III) and others. Complexation of monosodium salt of 5-methyl-(pyridyl-2-azo)-1.8-aminonaphthol-2.4-disulfonic acid (HR, 5MPAANS.S-2.4) with zinc(II) and copper(II) ions has been investigated in aqueous solutions by spectrophotometric method. The formation of complex compounds of 5MPAANS.S-2.4 with zinc(II) and copper(II) ions in a ratio 2:1 was established. The sensitivity of the determination method of zinc(II) and copper(II) was determined (pH_Zn=6.50; pH_Cu=4.0; ε_ZnR=42017, ε_CuR=20000; ε_HR=3306, К_eq.ZnR=1.26∙10^-4; К_еq.CuR=2.73; Δλ_ZnR=55 nm, Δλ_CuR=90 nm, K_dis.НR=2.95∙10^-8). МR₂ complex compound is synthesized. The selectivity of 5MPAANS.S-2.4 to zinc(II) and copper(II) ions has been investigated. Suggested spectrophotometric method of definition was applied in the analysis of model mixtures, industrial alloys based on aluminum and natural water and obtained results were metrologically evaluated.

Key words: Zinc(II), copper(II), organic reagent, sensitivity, model mixture, rainwater, industrial alloys, Omonhon’s spring.