engleski

Electrochemical response of cooper at histidine self assembled gold electrode

Modification of the gold electrode by self assembled histidine monolayer was performed in aim to obtain sensor surface selective for determination of Cu(II) ion from aqueous solution or from Cu(II)-histidine aqueous solution. In aqueous solution, histidine makes bidentante or tridentates complex, coordinating copper by carboxylate group and primary or secondary amine groups. Liedberg et al. [1] described oxygen coordination between the carboxylate group of histidine and gold surface. In that case, metal cation can only be coordinated between the primary and secondary amine groups of histidine. Formation of histidine layer on the gold surface was tested by electron transfer from solution through histidine monolayer using p- benzoquinone/hydroquinone redox couple. Electrochemical responses of gold electrode and gold histidine modified electrode were tested by cyclic voltammetry. Accumulation of Cu(II) was carried out by immersion of the Au-His modified electrode into Cu(II) solution or Cu(II)-histidine complex under open circuit potential. A stock solution of His-Cu(II) complex (20 mM) was prepared in deinoized water and was successively diluted for preparation of standard solutions in the range between 10-8 and 10-4 M. Adsorptive stripping voltammetry was used for determination of metal cation coordinated to a self assembled histidine as ligand positioned on the top of gold electrode. Electrode response (log(I)) was linearly proportional to log(Cu(II)) and log(Cu- His) concentration and obtained coefficient of correlation were R2 = 0, 9945 and R2 = 0, 9987 respectively.

Gold electrode; Histidine; Self-assembled monolayer; Adsorptive anodic stripping voltammetry

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