Electrochemical Study of Cadmium (II) Complexation with Cysteine
- 1 Hydrometeorological Service of Macedonia, Skopje, Macedonia
- 2 Rudjer Bo?kovi? Institute, Division for Marine and Environmental Research, Zagreb, Croatia
- 3 Department of Chemistry, University of Prishtina, Prishtina, Kosovo
Abstract
The complexation of Cd with cysteine has been investigated at pH ~9, and in constant ionic medium 0.59 M NaNO 3 and borate buffer. Reduction signals of the hydrated Cd 2+ and Cd-cysteinate complex were resolved on the potential scale during amperometric titration of 2 × 10 - 6 M Cd 2+ with cysteine and cysteine with Cd 2+ , in a differential pulse (DP) mode on HMDE. The 1:1 molar ratio of Cd 2+ to cysteine, and cysteine to Cd 2+ , was defined for Cd-cysteinate complex formed under the defined conditions. The appearance of the prepeak on the Cd-cysteinate reduction signal is showed, as the result of cysteine adsorption in reduced form. From the mass balance equations , the stoichiometric stability constants of Cd-cysteinate complex were calculated. Under various experimental conditions , comparable log K values were obtained. The grand average log K = 7.83 M - 1 refers to 0.59 M ionic strength and 23℃.
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