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Kinetic determination of cysteine and thiosulphate by inhibition of Hg (II) catalysed ligand substitution reaction

Naik, R.M. and Sarkar, J. and Prasad, Surendra (2008) Kinetic determination of cysteine and thiosulphate by inhibition of Hg (II) catalysed ligand substitution reaction. Microchemical Journal, 88 (1). pp. 45-51. ISSN 0026-265X

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Abstract

The sulphur containing inhibitors (I), cysteine (Cys) and sodium thiosulphate (THS), have been found to inhibit Hg(II) catalyzed exchange of cyanide in hexacyanoferrate(II) by nitroso-R-salt (NRS). The inhibitory effect of both the ligands are attributed to their binding tendencies with Hg (II) leading to the formation of catalyst-inhibitor (C-I) complex. The reactions have been followed spectrophotometrically in aqueous medium at 720 nm by noting the increase in absorbance of the green colour product, [Fe(CN)5NRS]3- at pH 6.50±0.02, temp 25.0±0.1 °C and ionic strength (μ) 0.1 M (KNO3). A most plausible mechanistic scheme involving the role of analytes (inhibitors) has been proposed. The values of equilibrium constants for complex formation between catalyst-inhibitor (KCI), catalyst-substrate (Ks) and Mechaelis-Menton constant (Km) have been computed from the kinetic data. The linear calibration curves have been established between absorbance and inhibitor concentrations under specified conditions. Cys and THS have been determined in the range 1-5 × 10-7 M and 4.9-16.9 × 10-7 M respectively. The detection limits have been computed to be 1 × 10-7 M and 4.9 × 10-7 M for Cys and THS, respectively.

Item Type: Journal Article
Subjects: Q Science > QD Chemistry
Divisions: Faculty of Science, Technology and Environment (FSTE) > School of Biological and Chemical Sciences
Depositing User: Users 24 not found.
Date Deposited: 08 Feb 2008 10:06
Last Modified: 16 Jul 2012 14:25
URI: http://repository.usp.ac.fj/id/eprint/4373
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