%0 Journal Article
%T Electrocatalytic Oxidation and Determination of Cysteine at Oxovanadium(IV) Salen Coated Electrodes
%A Piyush Kumar Sonkar
%A Vellaichamy Ganesan
%A Vijay Rao
%J International Journal of Electrochemistry
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/316254
%X A transition metal complex, oxovanadium(IV) salen (where salen represents N,N¡ä-bis(salicylidene)ethylenediamine) is immobilized on glassy carbon (GC) electrodes and utilized for electrocatalytic oxidation of cysteine. In presence of oxovanadium(IV) salen, increased oxidation current is observed due to the effective oxidation of cysteine by the electrogenerated oxovanadium(V) salen species. The oxidation current linearly varies with the concentration of cysteine from 0.1 to 1.0£¿mM. The modified electrode has good sensitivity and low limit of detection. These properties make the oxovanadium(IV) salen as an effective electrocatalyst for the determination of cysteine. 1. Introduction Transition metal complexes of N,N¡ä-bis(salicylidene)ethylenediamine (salen) are used as effective catalysts for several reactions including some electrochemical reactions [1, 2]. A variety of catalytic reactions are reported by metal salen complexes. For example, oxovanadium(IV) salen (VO2+-S) complex exhibits effective and selective catalysis for the conversion of aromatic and aliphatic aldehydes to cyanohydrin [3, 4]. Similarly, a number of metal complexes of vanadium(IV) which possess VO2+ unit have been synthesized and studied for their catalytic properties [5]. The catalytic efficiency and other characteristics of oxovanadium(IV) compounds depend on the nature of ligand, coordination number, and stereochemistry [6]. VO2+-S is already used for the electrocatalytic oxidation and subsequent determination of pyridoxine [7], ascorbic acid [8], sulphide [9], cysteine [6], and other analytes [10¨C12]. Recently, accurate determination of cysteine has attracted many researchers due to its important role in structural and functional modification of proteins [6]. Oxidation of cysteine gives information about structural and functional modification of proteins and it could be used as a destined radiation protector and cancer indicator [13, 14]. Thus, quantitative determination of cysteine and elucidating the cysteine oxidation mechanism are important in the protein chemistry [15, 16]. Cysteine oxidation and subsequent determination at bare electrodes suffer because of electrode fouling, low sensitivity, and high oxidation overpotential [5, 6]. These problems can be solved partially by the utilization of modified electrodes which normally contain a suitable electrocatalyst immobilized on the electrode surface [17, 18]. Electrocatalysts can be immobilized on the electrode surface in various ways using polymers containing covalently attached electrocatalyst, electrocatalyst immobilized
%U http://www.hindawi.com/journals/ijelc/2014/316254/