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The reduction of l-cystine in hydrochloric acid at mercury drop electrodes

Ralph, T.R., Hitchman, M.L., Millington, J.P. and Walsh, F.C. (2006) The reduction of l-cystine in hydrochloric acid at mercury drop electrodes Journal of Electroanalytical Chemistry, 587, (1), pp. 31-41. (doi:10.1016/j.jelechem.2005.10.005).

Record type: Article


The reduction of L-cystine in 0.1 mol dm3 HCl at 298 K has been studied at mercury electrodes. Dropping mercury electrode (DME), static mercury drop electrode (SMDE) and hanging mercury drop electrode (HMDE) modes were used with normal, sampled d.c. and differential pulse polarographic detection. The charge transfer kinetics for the irreversible reduction of L-cystine were complicated by reactant and product adsorption, by the formation of cysteinate complexes between mercury and the product thiol as well as by formation of Hg2Cl2. High Tafel slopes of 182 mV per decade were observed with a cathodic transfer coefficient of 0.32. The diffusion coefficient of L-cystine was found to be 5.3 · 10-10 m2 s-1 in 0.1 mol dm-3 HCl and 4.2 · 10-10 m2 s-1 in 2.0 mol dm-3 HCl at 298 K. The mechanism of L-cystine reduction at mercury has been discussed and the effects of pH and reactant concentration have been quantified.

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Submitted date: 11 August 2005
Published date: 3 February 2006
Keywords: Amino acids, Disulphide adsorption, Cysteinate formation, l-cystine, l-cysteine, Mercury electrodes, Linear sweep voltammetry, Cyclic voltammetry, Polarography, HMDE, SMDE, DME
Organisations: Engineering Mats & Surface Engineerg Gp


Local EPrints ID: 49021
ISSN: 1572-6657
PURE UUID: fb01d0f1-ab89-436d-bad3-31fa7fea2016

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Date deposited: 19 Oct 2007
Last modified: 17 Jul 2017 14:57

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Author: T.R. Ralph
Author: M.L. Hitchman
Author: J.P. Millington
Author: F.C. Walsh

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