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Preparation and Characterization of New Carbon Paste Microelectrode Modified with potassium hydrotris{N-(2,6-xylyl)-2- thioimidazolyl)}borate and Its Application in the Voltammetric Determination of Hg (II)

Gaber A. M. Mersal and Mohamed M. Ibrahim

A new carbon paste microelectrode modified by potassium hydrotris{N-(2,6-xylyl)-2-thioimidazolyl)}borate was developed for the electrochemical determination of Hg(II) by square wave voltmmetry. The electrochemical behavior of Hg(II) was studied on the modified electrode in the absence and presence of potassium hydrotris{N-(2,6- xylyl)-2-thioimidazolyl)}borate using cyclic voltammetric techniques. At the surface of the prepared electrode, Hg(II) showed a well defined redox couple system, the anodic and cathodic peaks appeared at about 0.14 and 0.01 V (vs. SCE), respectively, with a potential difference (ΔEp) about 130 mV. Using square wave voltammetry, Hg(II) gave a well defined oxidation peak. The effect of different experimental parameters was optimized to get the highest peak current for the electrochemical determination of Hg(II) using square wave voltammetry. The effect of some interference due to the presence of other heavy metals on the peak height of Hg(II) was studied. Under the optimum conditions, a linear relationship existed between the currents and the concentrations of Hg(II) in the range from 1x10-6 M to 1x10-4 M with the detection limit of 1.7x10-7 M. This method was applied for the determination of Hg(II) different water samples and the resulted data was compared by the data obtained from the standard ICP-AES instrument.