Voltammetric Determination Of Cadmium Research Articles

Voltammetric determination of cadmium(II), lead(II) and copper(II) with a glassy carbon electrode modified with silver nanoparticles deposited on poly(1,8-diaminonaphthalene).

A glassy carbon (GC) electrode was modified with poly(1,8-diaminonaphthalene) (p-1,8-DAN) that was coated with silver nanoparticles (Ag NPs) (size: 10.0-60.0nm by TEM) by electrodeposition process using cyclic voltammetry (CV) technique. The resulting nanocomposite was characterized by FE-SEM, AFM, EDX, XPS, TEM and XRD. The surface area and the electrochemical characteristics of the electrode were investigated by CV and square wave voltammetry (SWV) techniques, and the probe preparation conditions were optimized. The electrode was used for individual and simultaneous determination of the heavy metal ions cadmium(II) (Cd2+), lead(II) (Pb2+) and copper(II) (Cu2+) in water samples by square wave anodic stripping voltammetry (ASV) using scan rate 0.005V. s-1. The probe showed well separated anodic stripping peaks for Cd2+, Pb2+, and Cu2+. Attractive features of the method include (a) peak voltages of -1.02, -0.78 and - 0.32V (vs. Ag/AgCl) for the three ions, and (b) low limits of detection (19, 30 and 6 ng.L-1, respectively. The electrode can also detect zinc(II) (Zn2+) and mercury(II) (Hg2+), typically at -1.36V and + 0.9, respectively. Graphical abstract Schematic presentation of simultaneous electrochemical determination of Pb2+, Cd2+, and Cu2+ at a poly(1,8-diaminonaphthalene)-modified glassy carbon electrode coated with silver nanoparticles.

Studies on voltammetric determination of cadmium in samples containing native and digested proteins

This work focuses on determination of cadmium ions using anodic stripping voltammetry (ASV) on thin film mercury electrode in conditions corresponding to those obtained after digestion of cadmium-based quantum dots and their conjugates. It presents the impact of selected proteins, including potential receptors and surface blocking agents on the voltammetric determination of cadmium. Experiments regarding elimination of interferences related to proteins presence using sodium dodecyl sulfate (SDS) are also shown. Effect of SDS on selected analytical parameters and simplicity of analyses carried out was investigated in the framework of current studies. The significant differences of influence among tested proteins on ASV cadmium determination, as well as the variability in SDS effectiveness as the antifouling agent were observed and explained. This work is especially important for those, who design new bioassays and biosensors with a use of quantum dots as electrochemical labels, as it shows what problems may arise from presence of native and digested proteins in tested samples.

Voltammetric Determination of Cadmium, Copper and Lead Using Glassy carbon Electrode

Cyclic voltammetry and linear sweep voltammetry were used to determine cadmium, copper and lead metal ions using glassy carbon electrode. From cyclic measurements, cadmium, copper and lead showed a well single anodic peak at -547, +191.5 and -520 mV respectively. Several parameters affecting the stripping current response were investigated and optimized. Under optimal conditions, the glassy carbon electrode showed a good linear response to Pb 2+ , Cd 2+ and Cu 2+ in the concentration range from 8x10 -6 M to 1x10 -4 M. The detection limits were 2x10 -7 M for Pb 2+ , 9x10 -7 M for Cd 2+ and 1x10 -7 M for Cu 2+ calculated for a single-to- noise ratio of 3 (S/N = 3). The proposed method was successfully applied for determining Pb 2+ , Cd 2+ and Cu 2+ contents in well water samples. I. Introduction Voltammetry refers to a class of electrochemical techniques in which the current at the working electrode is measured as a function of potential waveform applied to the electrode. The potential of this electrode serves as the driving force for the reaction; i.e. it is controlled parameter that causes the chemical species present in the solution to be electrolyzed (reduced or oxidized) at the surface. The reducing or oxidizing strength of the electrode is controlled by the applied potential (1).

Voltammetric determination of cadmium (II) based on a composite film of a thiol-functionalized mesoporous molecular sieve and an ionic liquid

A composite film made from a thiol-functionalized mesoporous molecular sieve and an ionic liquid is introduced for use in a voltammetric sensor for Cd(II). The electrode exhibits excellent sensitivity towards Cd(II) in showing a markedly increased stripping peak current. Following the optimization of the experimental parameters, a linear response is obtained in the concentration range from 29 nM to 0.87 mM of Cd(II). The detection limit is as low as 1.0 nM (at S/N = 3) after an accumulation at −1.1 V for 4 min. The method was successfully applied to determine Cd(II) in water samples. Features such as large electroactive area, fast electron transfer and low background current make this electrode a promising platform for fabricating reliable electrochemical sensors for various species, such as heavy metals and environmental pollutants.

Optimization of Mercury Thin Film Electrodes for Sono-ASV Studies

The feasibility of using Nafion-coated mercury thin film electrodes on glassy carbon, iridium and platinum as substrates for anodic stripping voltammetric determination of cadmium and lead in the presence of ultrasound is examined. Glassy carbon was found to be the most appropriate substrate material for these electrodes. Nafion-coated glassy carbon mercury thin film electrodes, NCGCMFE's, were mechanically resistant under sonication, as shown by AFM imaging. These electrodes showed higher sensitivity (up to 170 times higher for cadmium depending upon deposition times) for the determination of cadmium and lead than glassy carbon mercury thin film electrodes formed without Nafion. A major factor contributing to this behavior appeared to be the greater mechanical stability of the mercury thin film provided by the Nafions-coating under conditions of high mass transport provided by ultrasound. In the case of iridium and platinum-based mercury thin film electrodes, which showed lower sensitivity than NCGCMFE's (14 and 1.4 times more sensitive than mercury films on iridium and platinum, respectively, for the determination of cadmium), the polymer-film became detached after short sonication times, precluding their use for analytical purposes.

Voltammetric determination of cadmium on a carbon paste electrode modified with a chelating resin

AbstractA method is described for determination of cadmium using a carbon pas electrode modified with Amberlite IRC 718 chelating resin and voltammetric measurement of the collected ion. Optimal conditions for the preconcentration of cadmium were 10 minutes stirring at open circuit in 0.001 M ammonium buffer, pH 9. For electrochemical measurements, the optimal parameters include the use of a 0.1 M HCl solution, a delay time of 36 seconds at −1.1 V (vs. Ag/AgCl) and a 400 mV/s scan rate. The well‐defined anodic peak at −0.7 V obtained is adequate for the quantitation of cadmium at very low concentration levels, with a detection limit of 0.005 mg/L. The method was used with good results for the determination of cadmium in polluted river waters.

Characterization and utilization of a long-lasting sessile-drop mercury electrode in differential pulse anodic-stripping voltammetric subtrace metal analysis of natural waters

Construction details and voltammetric characterization of a long-lasting sessile-drop mercury electrode are reported. The results obtained in the fully automated differential pulse anodicstripping voltammetric determination of cadmium in a simple purified electrolyte as well as of zinc, cadmium and lead in sea-water samples suggest that this new kind of semi-stationary mercury electrode may be employed in voltammetric trace and ultratrace analysis of natural waters for metal ions.