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Kinetic determination of organosulphur ligands by inhibition: trace determination of cysteine and maleonitrilodithiolate [MNDT]

Prasad, Surendra (2007) Kinetic determination of organosulphur ligands by inhibition: trace determination of cysteine and maleonitrilodithiolate [MNDT]. Microchemical Journal, 85 (2). pp. 214-221. ISSN 1095-9149

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Abstract

Some organosulphur ligands have been found to inhibit the mercury(II) catalyzed substitution of cyanide in hexacyanoferrate(II) by N-methylpyrazinium ion (Mpz+). The inhibitory effect is due to the binding tendency of catalyst Hg2+ with these inhibitors. This effect has been used as a basis to develop a kinetic method for the determination of trace amounts of two organosulphur ligands viz. cysteineand MNDT. The reaction was followed spectrophotometrically at 655 nm by measuring the decrease in absorbance of the product [Fe(CN)5Mpz]2−. The influence of the reaction variables has also been studied. A general mechanistic scheme of the indicator reaction system including the role of inhibitor has been proposed and applied to determine the organosulphur ligands. Under the selected experimental conditions cysteine and MNDT have been determined in the range of 2–20 × 10− 7 M and 5 × 10− 8 M to 12 × 10− 7 M respectively in various aqueous samples. The analytical concentration range depends upon the amount of Hg2+present in the indicator reaction and also on the stability of the Hg2+-inhibitor complex in question. Under specified conditions, the detection limit for cysteine and MNDT are 2 × 10− 7 M and 5 × 10− 8 M respectively. The influences of possible interference by major amino acids, on the determination of cysteine and their limits have been investigated.

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: Ms Mereoni Camailakeba
Date Deposited: 27 May 2007 10:08
Last Modified: 17 Jul 2012 17:01
URI: http://repository.usp.ac.fj/id/eprint/821
UNSPECIFIED

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