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METHODS AND OBJECTS OF CHEMICAL ANALYSIS

(Metody i Ob''ekty Himicheskogo Analiza)

An international journal devoted to all aspects of Analytical chemistry

ISSN 2413-6166 (Online), ISSN 1991-0290 (Print)

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Redox-reaction Products of 4-sulfo-2-(4'-sulfonaphthalene-1'-azo) naphthol-1 with Ce(IV) - New Analytical Forms for its Quantitative Determination

A.N. Chebotarev*, I.S. Efimova, E.V. Raboshvil, E.M. Rakhlitskaya

* Corresponding author

Odessa I.I. Mechnikov national university, Department of analytical chemistry, Dvoryanskaya St., 2, Odessa, Ukraine, 65082;
*e-mail: alexch@ukr.net

Methods Objects Chem. Anal., 2018, 13(4), p. 167-176

https://doi.org/10.17721/moca.2018.167-176 

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Abstract

The results of redox interaction of Ce (IV) with 4-sulfo-2-(4’-sulfonaphthalene-1’-azo) naphthol-1 (carmosine- KAN) in aqueous solutions (pH 1.75) have been presented. The destructive oxidation of CAS into two fragments (2-nitroso-4-sulfonaphthol-1 (L1) and 1-nitroso-4-sulfonaphthalene (L2)) is accampanied by reduction of Ce(IV) to Ce(III). It was found that an increase in the Ce(III) -L1 -L2 system acidity to pH ~ 11 leads to formation of the [Ce(III)(ОН)2·L1·2Н2О] complex. After acetonitrile is introduced to [Ce(III)(ОН)2·L1 ·2Н2О] – L2 system (up to 40 % by volume) self-organization of products involving CH3CN is observed. The resulting water-acetonitrile system becomes turbid, and after ~10 min phase separation is observed. Phase I contains a solvate {L2·(CH3CN)п } of «straw» color (360 nm) and phase II (lower layer) contains solvated complex {[Ce (III) (ОН) 2 ·L 1 ·(CH 3 CN) 2 ]·(CH 3 CN)n} of «blue» color (640 nm). The use of these solvates allows determination of Ce(IV) in the range 2.2 ÷ 50.1 μg/cm3 (y = 0.5526с + 0.0575, R2 = 0.9917, ε360 = 6.2·103) and 4.2 ÷ 84.0 μg/cm3 (y = 0.1862c + 0.0265, R2 = 0.9952, ε640 = 2.05·103), respectively. The revealed dependence was used for indirect (volumetric) determination of Ce(IV) (y = -0.7857c + 20.4440, R2=0.9988). The methods was tested on standard samples of mineral origin and herbal pharmaceutical preparations.

Keywords: cerium, carmosine, oxidation-reduction, complexation, spectrophotometry, two-phase system,
determination techniques

Article language: Rus


Publisher:Taras Shevchenko National University, Kiev Ukraine

(Analytical chemistry department at Taras Shevchenko National University, 64 Vladimirskaya STR., Kiev, 01601 UKRAINE)
analysis@univ.kiev.ua, www.achem.univ.kiev.ua, +380-44-2393345

Papers published in Methods and Objects of Chemical Analysis are considered as publications suitable for PhD thesis

The journal website: www.moca.net.ua