Spectrophotometric Determination of Microconcentrations of Zinc(II) and Copper(II) in Water and Industrial Alloys Using a New Chromogenic Reagent [4-Amino-5-hydroxy-6-[(5-methyl-2-pyridyl)azo]-3-sulfo-1-naphthyl]sulfonyloxysodium
نویسندگان
1 Department of Chemistry, National University of Uzbekistan named after Mirzo Ulugbek, 100174, Tashkent, Uzbekistan, 2.Department of Biochemistry and Physiology, Tashkent State Agrarian University, 100020, Tashkent, Uzbekistan
2 Institute of Polymer Chemistry and Physics Uzbekistan Academy of Sciences, Tashkent, Uzbekistan
3 Faculty of Pharmacy, Tashkent Pharmaceutical Institute, Tashkent, Uzbekistan
4 Department of Chemistry, National University of Uzbekistan named after Mirzo Ulugbek, 100174, Tashkent, Uzbekistan
5 Associate Professor of analytical chemistry Department, the National University of Uzbekistan
6 Department of Chemistry, National University of Uzbekistan named after Mirzo Ulugbek, 100174, Tashkent, Uzbekistan
7 Department of Chemistry, Denov Institute of Entrepreneurship and Pedagogy, 190507, Denov, Uzbekistan
8 Department of Chemistry, National University of Uzbekistan named after Mirzo Ulugbek, 100174, Tashkent, Uzbekistan
9 Faculty of Pharmacy, Tashkent Pharmaceutical Institute, Tashkent, Uzbekistan
doi
10.22034/crl.2024.457689.1338چکیده
The present study aimed to develop a new spectrophotometric method for the determination of zinc(II) and copper(II) using a new chromogenic reagent, [4-amino-5-hydroxy-6-[(5-methyl-2-pyridyl)azo]-3-sulfo-1-naphthyl]sulfonyloxysodium (HR). The complexation of Zn(II) and Cu(II) with HR was studied spectrophotometrically at absorption maxima of 565 nm (Δλ=55 nm) and 595 nm (Δλ=90 nm) for Zn-HR and Cu-HR, respectively. The HR reagent interacts with Zn(II) and Cu(II) instantaneously at pH 6.5 and pH 4.0, respectively, and the absorbance of the solution is stable for 70 and 1440 minutes, respectively. Using isomolar series, Asmus straight line, equilibrium shift and spectrophotometric titration methods, the stoichiometries of the complexes were found to be 1:2 metal-to-ligand ratios for Zn and Cu. To determine the charge of the complex, the solution was passed through columns containing the cations KU-2 and KRS-10 and the anions AB-16-GS and AN-2FN. In this case, one proton is released from the reagent molecule, and a chelate cycle is formed mainly through the atoms of the oxygen-OH group, the nitrogen of the pyridine ring and the N=N group. The dilute Babko method was used to estimate the stability constant (Kstab) values, which were found to be on the order of 1.44∙1021 (lgβ=21.16) and 2.97∙1017 (lgβ=17.47) for the Zn and Cu complexes, respectively. The proposed spectrophotometric methodology established that the concentrations of zinc(II) and copper(II) could be estimated to be 1.0-18.0 and 0.50-6.50 ppm, respectively, corresponding to molar absorptivities of 4.2∙104 and 2.0∙104 l/mol∙cm, respectively (εHR=3.3∙102, Kdis., HR=2.95∙10-8, pK=7.53). Likewise, the formed complexes were stable at different pH values, allowing the simultaneous estimation of the two metals. The suggested spectrophotometric method of definition was applied in the analysis of model mixtures, industrial alloys based on aluminum and natural water, and the obtained results were metrologically evaluated (Sr=0.043)
