Stripping Voltammetry Of Copper Research Articles

Square wave anodic stripping voltammetry of copper(II) at a MWCNT paste electrode modified with a tetracarbonylmolybdenum(0) nanocomposite

The article reports on a MWCNT paste electrode modified with the fenchone diazine tetracarbonylmolybdenum(0) complex, and on its application to sensitive determination of Cu(II) by using square wave anodic stripping voltammetry. Under optimal conditions and at a typical working voltage of 33 mV (vs. Ag/AgCl), response is linearly related to the concentration of Cu(II) in the 0.1 nM to 1.0 μM range, and the limit of detection is 80 pM. The relative standard deviation [for n = 5 and at a 1.0 μM concentration of Cu(II)] is 3.6 %. Unlike Pb(II), the ions Ni(II), Mg(II), Cd(II), Co(II), Hg(II), and Zn(II) do not strongly interfere. Electrochemical impedance spectroscopy reveals a fast charge transfer at the electrode-solution interface. The method was applied to the analysis of Cu(II) in water samples, and the results agreed well with those obtained by ICP-OES.

Voltammetric behaviour at gold electrodes immersed in the BCR sequential extraction scheme media: Application of underpotential deposition–stripping voltammetry to determination of copper in soil extracts

The development of mercury-free electroanalytical systems for in-field analysis of pollutants requires a foundation on the electrochemical behaviour of the chosen electrode material in the target sample matrices. In this work, the behaviour of gold working electrodes in the media employed in the BCR sequential extraction protocol, for the fractionation of metals in solid environmental matrices, is reported. All three of the BCR sequential extraction media are redox active, on the basis of acidity and oxygen content as well as the inherent reducing or oxidising nature of some of the reagents employed: 0.11 M acetic acid, 0.1 M hydroxylammonium chloride (adjusted to pH 2) and 1 M ammonium acetate (adjusted to pH 2) with added trace hydrogen peroxide. The available potential ranges together with the demonstrated detection of target metals in these media are presented. Stripping voltammetry of copper or lead in the BCR extract media solutions reveal a multi-peak behaviour due to the stripping of both bulk metal and underpotential metal deposits. A procedure based on underpotential deposition–stripping voltammetry (UPD-SV) was evaluated for application to determination of copper in 0.11 M acetic acid soil extracts. A preliminary screening step in which different deposition times are applied to the sample enables a deposition time commensurate with UPD-SV to be selected so that no bulk deposition or stripping occurs thus simplifying the shape and features of the resulting voltammograms. Choice of the suitable deposition time is then followed by standards addition calibration. The method was validated by the analysis of a number of BCR 0.11 M acetic acid soil extracts. Good agreement was obtained been the UPD-SV method and atomic spectroscopic results.

Stripping voltammetry of copper and lead using gold electrodes modified with self-assembled monolayers

One problem associated with using bare solid metal electrodes, such as gold and platinum, in stripping analysis to determine heavy metal ions such as lead and copper ions in dilute solutions is that underpotential deposition (UPD) gives multiple stripping peaks in the analysis of mixtures. These peaks are often overlapped and cannot be conveniently used for analytical purposes. Bifunctional alkylthiols, such as 3-mercaptopropionic acid, with an ionizable group on the other terminal end of the thiol can form self-assembled monolayers (SAMs) on the surface of the gold electrode. It is shown that such an SAM-modified gold electrode minimizes the UPD effects for the stripping analysis of lead and copper. The anodic peak potential shifts and the peak shape changes, indicating that the SAM changes the deposition and stripping steps of these heavy metal ions. Thus, the sensitivity levels for both single species and mixtures can be significantly improved for the conventional solid electrodes. The mechanism of the deposition reaction at the SAM-modified gold electrodes is discussed.

Linear scan stripping voltammetry of copper(II) at the chemically modified carbon paste electrode

A new chemically modified electrode (CME), α-benzoinoxime (CUPRON) modified carbon paste electrode, for determining copper(II) is reported because of its excellent selectivity and sensitivity. The electrode is made by mixing a quantity of CUPRON (25%, w/w) with graphite powder (50%, w/w) and paraffin oil (25%, w/w). The CME preferentially deposits copper from the pH 8.5 NH3-NH4Cl buffer solution containing copper(II) under an open circuit and most of metal ions do not interfere with the measurements. The detection limit (S/N of three) for determining Cu(II) is 3 × 10−10 g/ml after 10 min accumulation in fast linear scan stripping voltammetric measurement. Linear calibration curves are obtained for Cu(II) concentration ranged from 1 × 10−8M to 1 × 10−6M. The response can be maintained with relative standard deviation of 6.0% in a 5 × 10−6M Cu(II) solution after eight accumulation/measurement/ regeneration cycles at the same electrode surface. The effect resulted from carbon paste preparation, reduction potential, electrode renewal, electrolyte and solution pH, preconcentration time, concentration dependence, possible interference and other variables has been evaluated. As for application, the CME demonstrates its high sensitivity and copper-selectivity in complex composition samples, such as anodic mud and polluted water.

Adsorptive accumulation voltammetry of copper(II) using complex formation reaction with salicylideneamino-2-thiophenol

The cathodic stripping voltammetry of copper(II) was investigated with a method, based on the adsorptive accumulation of the Cu(II)-salicylideneamino-2-thiophenol (SATP) complex on a hanging mercury drop electrode. The copper(II)-SATP complex could be accumulated on the electrode at −0.20 V in 0.01 mol/l nitric acid. The reduction peak of the copper complex was observed by scanning the potential in a negative direction in the differential pulse mode. The calibration curve for copper was linear over the range 5×10−9–1×10−7 mol/l. This method was applied to determine copper(II) in GSJ (Geological Survey of Japan) standard rock reference materials.

Anodic stripping voltammetry of copper and bismuth

Microgram and nanogram quantities of copper and bismuth are electrodeposited on a glassy carbon electrode from 10M hydro-fluoric-1M nitric acid solutions. The deposit is then anodically removed in 0.1M perchloric acid or 0.1–12M hydrochloric acid, a current-voltage curve being recorded. Copper and bismuth at p. p. b. levels in sponge zirconium are determined by this technique with 5 M hydrochloric acid as stripping electrolyte within 3 hours.