Original scientific paper

Stability Constants of Cobalt(II) and Copper(II) Complexes with 3-[(o-Carboxy-p-nitrobenzene)azo]chromotropic Acid and Selective Determination of Copper(II) by Competition Coordination

Hong-Wen Gao ; State Key Laboratory of Pollution Control and Resource Reuse Research, School of Environmental Science and Engineering, Tongji University, Shanghai-200092, P. R. China
Jian-Fu Zhao ; State Key Laboratory of Pollution Control and Resource Reuse Research, School of Environmental Science and Engineering, Tongji University, Shanghai-200092, P. R. China

Abstract

A method for selective determination of copper(II) based on the reactions of copper(II) or cobalt(II) with 3-[(o-carboxy-p-nitrobenzene)azo]chromotropic acid (CNBAC) at pH = 11.4 was developed. Results have shown that two complexes, Co(CNBAC)2 and Cu(CNBAC), were formed, whose cumulative stability constants were 5.22 × 109 and 7.61 × 105 dm3 mol–1, respectively, and their molar absorption coefficients were 1.19 × 104 and 2.12 × 104 dm3 mol–1 cm–1 at 610 nm. The competition coordination of CuII and CoII with CNBAC was applied for selective determination of CuII by the spectral correction technique. In the absence of any masking reagent, the recommended method was selective and was applied for quantitative determination of copper(II) in river and waste water samples.

Keywords

competition coordination for selective determination; spectral correction technique; determination of copper(II); stability constants; 3-[(o-carboxy-pnitrobenzene)azo]chromotropic acid

Hrčak ID:

103051

URI

https://hrcak.srce.hr/103051

Publication date:

30.4.2003.

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