Collect. Czech. Chem. Commun.
2009, 74, 1715-1725
https://doi.org/10.1135/cccc2009111
Published online 2010-02-04 20:28:09
Voltammetric studies of the Co(II)-tris(hydroxymethyl)aminomethane and sodium perborate volumetric catalytic system
Jerzy Zarębski, Andrzej Bobrowski*, Agnieszka Królicka and Maria Putek
Department of Building Materials Technology, Faculty of Materials Science and Ceramics, AGH – University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków, Poland
Abstract
It has been shown that in the tris(hydroxymethyl)aminomethane (THAM)/HCl buffer, Co(II) ions catalyze the oxidation of THAM by sodium perborate. The reaction occurs at boiling temperature, and the product of the catalytic THAM oxidation, tris(hydroxymethyl)nitrosomethane, gives a well-defined quasireversible cathodic wave preceding that of the Co(II) ions by about 160 mV. The voltammetric responses of this product are proportional to the amount of sodium perborate and to the concentration of Co(II) ions. In the volumetric catalytic system of Co(II) ions/THAM/sodium perborate, the sensitivity of the determination of Co(II) is increased by one to two orders of magnitude, depending on the voltammetric technique used. Prior to the detection of tris(hydroxymethyl)nitrosomethane, EDTA was added to the solution to form voltammetrically inactive complexes with Co(II) and other interfering ions. Therefore, this method may be applied for the determination of Co(II) ions at low concentrations in the presence of a large excess of interfering ions, in particular Ni(II) and Zn(II).
Keywords: Volumetric catalytic system; Tris(hydroxymethyl)aminomethane (THAM); Sodium perborate; Cobalt; Voltammetry; Electrochemistry.
References: 24 live references.
