Voltammetric Determination Of Copper Research Articles

Voltammetric determination of copper and zinc in water using a Ruthenium bipyridyl/Nafion-modified indium tin oxide-coated glass electrode

Chemically-modified Indium Tin Oxide (ITO) coated glass substrates were fabricated by depositing Nafion thin films doped with tris (2,2’-bipyridyl) ruthenium(II) dichloride hexahydrate via drop coating deposition technique. The Nafion volume concentration in the film is 1% (v/v) and the mediator concentration is 5 mg per 1 mL Nafion. The chemically-modified electrodes were characterized by cyclic voltammetry (CV) and were used as working electrodes to detect varying concentrations of copper (Cu2+) and zinc (Zn2+) in a 0.1 M NaCl supporting electrolyte solution via Anodic Stripping Voltammetry (ASV). Cu2+ and Zn2+ ions were successfully determined by ASV. The limits of detection for Cu2+ and Zn2+ were 0.1 ppm and 0.7 ppm, respectively. The modified electrodes were used to determine the presence of Cu2+ and Zn2+ in different real water samples. The presence of Cu2+ was successfully determined in deep well, lake, and tap water samples, while the presence of Zn2+ was successfully determined in sea and tap water samples. Atomic Absorption Spectroscopy (AAS) results confirm the presence of Cu2+ and Zn2+ in the samples.

Voltammetric determination of copper with proton pump inhibitor drug omeprazole

The electrochemical behavior of copper(II)-omeprazole complex was studied by differential pulse and cyclic voltammetry at a hanging mercury drop electrode. A well-defined voltammetric peak was obtained at −0.6 V (vs. Ag/AgCl sat’d KCl) in phosphate buffer (pH 7). The experimental results show that the reduction of the copper(II)-omeprazole complex is irreversible. The stoichiometry and stability constant of the Cu(II)-omeprazole complex were evaluated using differential pulse cathodic adsorptive stripping voltammetry and found to be 1 : 2 and 1.39 × 1011 M−1. The limits of detection and quantitation were found to be 3 × 10−9 and 1 × 10−8 M, respectively. The proposed procedure was successfully applied for the determination of trace level of copper in bottled natural drinking water samples.

Voltammetric Determination of Copper and Lead in Gasoline Using Sample Preparation as Microemulsions

A voltammetric method for the determination of Cu(II) and Pb(II) in gasoline using sample preparation as three-component solutions (gasoline:propan-1-ol:water, 25:60:15 v/v/v) is proposed. HNO(3) was employed as a supporting electrolyte and to allow the use of aqueous inorganic standards for calibration, even if the analyte species originally in gasoline is present as a metallo-organic form. A square-wave anodic sequential determination was used by measuring the stripping current of Cu(II) (at +104 mV) using a glassy carbon electrode (GCE) and, in a second run, measuring the Pb(II) stripping current (at -470 mV) using a bismuth-film deposited on the surface of the GCE. The method allowed the quantification of 1.7 x 10(-9) mol L(-1) of Cu and 1.4 x 10(-10) mol L(-1) of Pb employing a 1500-s accumulation time. Recovery tests using analyte spiked three-component solutions prepared with commercial gasoline samples enabled recoveries of Cu and Pb from 97 +/- 8 to 102 +/- 5%.

Voltammetric determination of copper at chemically modified electrodes based on crown ethers.

The feasibility of fabricating copper-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and in 40% (v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing the crown ethers into a graphite powder-paraffin oil matrix. The electrodes so formed were able to bind Cu(II) ions chemically and gave better voltammetric responses than the unmodified ones. The crown ethers studied and compared were 15-crown-5, benzo-15-crown-5 and dibenzo-18-crown-6. With a 3% benzo-15-crown-5 CME, Cu(II) could be quantified at sub-ppm levels by differential pulse voltammetry with a detection limit of 0.05 ppm. By differential pulse anodic stripping voltammetry Cu(II) could be quantified over the range I to 100 ppb. Interference from metal ions like Ni(II), Co(II), Mn(II), Fe(II), etc. have also been studied. The method was successfully applied to artificial as well as commercial samples of alcoholic beverages.

Modelling the matrix interference of iron in the multivariate determination of copper by stripping voltammetry: Instrument standardization

Two different standardization procedures have been applied in order to minimize the experimental effort necessary to determine copper in presence of iron by differential pulse anodic stripping voltammetry. The significant matrix interference caused by iron in the voltammetric determination of copper has been successfully solved by using partial least squares (PLS) regression. The use of this multivariate regression implies a large number of training set samples, so a standardization method was required. In fact, the standardization methods used have reduced the calibration samples needed in future determinations by up to 75%. Moreover, PLS regression allowed both metals to be determined simultaneously by using an adequate experimental design, without any limitation to their respective concentrations and without the need to know the level of interference.

Extraction and voltammetric determination of copper, lead, cadmium and zinc in iron ore samples

A simple, rapid and precise method of determining heavy metals (copper, lead, cadmium and zinc) in iron ores using differential-pulse anodic-stripping voltammetry (DPASV) is proposed. The sample is digested with concentrated hydrochloric acid and iron is removed by extraction with diethyl ether. The aqueous acidic extract is subjected to voltammetry. Recoveries for these four metals range from 93.5 to 101.0%. The relative standard deviations for copper, lead, cadmium and zinc are 0.72, 0.48, 0.64 and 0.47%, respectively. The critical value of |t| at the 95% confidence level indicates that there is no systematic error in the proposed method.

Ethylenediamine in the voltammetric determination of copper in sea water at a rotating mercury film electrode

The use of ethylenediamine in the voltammetric study of copper in natural sea water was evaluated for applicability with rotating thin mercury film electrodes. It was shown that this method increases the analytical sensitivity for copper at such electrodes by at least a factor of 4, and improves the detection of pH 8 labile copper.

Adsorption voltammetry of the copper(II) 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex

The voltammetric determination of copper(II), based on adsorptive accumulation of the Cu(II)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (S-Br-PADAP) complex on a hanging mercury drop electrode, is reported. The complex can be accumulated at the electrode at constant potential in 0.1 M ammonium nitrate/ammonia buffer solution, and its reduction wave observed by scanning the potential in the negative direction, in the differential pulse mode. The calibration graph for copper is linear over the range 0.05–0.5μ M, with accumulation for 5 min at −0.20 V. The adsorption of the complex is discussed and compared with that of copper complexes with several other pyridylazo derivatives.

Electrochemical stripping determination of traces of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide

Procedures have been developed for the determination of copper, lead, cadmium and zinc in zirconium metal and zirconium dioxide, at concentrations of 1 ppm or less. Zirconium metal was dissolved in suphuric acid, and zirconium dioxide decomposed under pressure with hydrofluoric acid. Sample solutions were prepared in dilute sulphuric acid. For the stripping determination, the sample solution was either mixed with a complexing tartrate base electrolyte or the pre-electrolysis was carried out in acid solution, with the acid solution being exchanged for a pure base electrolyte ( e.g. an acetate buffer) for the stripping step. The stripping step was monitored by d.c., differential pulse and Kalousek commutator voltammetry and the three methods were compared. A stationary mercury-drop electrode can generally be used for all the methods, whereas a mercury-film electrode is suitable only for the d.c. voltammetric determination of copper, lead and cadmium, as pulse measurements with films are poorly reproducible and the electrodes are easily damaged. The relative standard deviation does not exceed 20%. Some samples contained relatively large amounts of copper, which is best separated by electrodeposition on a platinum electrode.

Voltammetric behaviour of copper(iii) and its analytical applications

Copper(II) and copper(III) complexes with periodate or tellurate ligands are electroactive at a smooth platinum electrode, giving an anodic, cathodic or cathanodic wave in the presence of alkaline hydroxide solutions containing copper(II), copper(III), or copper(II)-copper(III) species, respectively. The corresponding limiting currents are diffusion-controlled. The following analytical applications are proposed: (a) amperometric titration of copper(III) solutions; (b) voltammetric determination of copper. Results of amperometric titrations of copper(III) were similar to those by an established procedure. Voltammetry of copper(II) allows the metal to be determined down to concentrations of 1·10 -5 M, even in the presence of different ions; the procedure can be applied to such heat-transfer media for nuclear reactors as sodium and potassium metals and their hydroxides.