Anodic Stripping Voltammetry at Bismuth-Coated and Uncoated Carbon Microdisk Electrodes:Application to Trace Metals Analysis in Flood Samples

This article reports on the performance of a bismuth-coated carbon microdisk electrode (BiFμE) for the determination of trace heavy metals by anodic stripping voltammetry (ASV). The BiFμE was prepared by electrodeposition of a metallic bismuth film onto the microdisk, by applying an in-situ electroplating procedure. To test the performance of the BiFμE, ASV measurements were performed on synthetic solutions containing Cd2+, Pb2+, and Cu2+ as target ions. The results indicated that cadmium and lead gave well-defined ASV peaks with no interference, and their quantitative determination could be carried out straightforwardly. In particular, linear calibration curves over the range 5.0 x 10-8-1.0 x 10-6M for both ions, and detection limits of 7.8 and 2.9 nM, for cadmium and lead, respectively, after applying a 60 sec preconcentration step, were obtained. The reproducibility was also satisfactory, the relative standard deviation (RSD) being within 2.5% for both ions. Copper, instead, gave an ASV response that. in most experimental conditions, overlapped with that of bismuth. This circumstance made the determination of copper at the BiFμE difficult. Since the latter element could be detected reliably at the uncoated carbon microdisk electrode (CμE), both BiFμE and CμE were employed, respectively, for the determination of lead and copper ions in drinking water, wine, and tomato sauce.

Sensitive determination of Cd and Pb by differential pulse stripping voltammetry with in situ bismuth-modified zeolite doped carbon paste electrodes

Here we investigated the analytical performances of the bismuth-modified zeolite doped carbon paste electrode (BiF-ZDCPE) for trace Cd and Pb analysis. The characteristics of bismuth-modified electrodes were improved greatly via addition of synthetic zeolite into carbon paste. To obtain high reproducibility and sensitivity, optimum experimental conditions for bismuth deposition Were Studied.

Narion/Poly(sodium 4-styrenesulfonate) mixed coating modified bismuth film electrode for the determination of trace metals by anodic stripping voltammetry

To improve the reproducibility, stability, and sensitivity of bismuth film electrode (BiFE), we studied the performances of a mixed coating of two cation-exchange polymers, Nafion (NA) and poly(sodium 4-styrenesulfonate) (PSS), modified glassy carbon BiFE (GC/NA-PSS/BiFE). The characteristics of GC/NA-PSS/BiFE were investigated by scanning electron microscopy and cyclic voltammetry. Various parameters were studied in terms of their effect on the anodic stripping voltarnmetry (ASV) signals. Under optimized conditions, the limits of detection were 71 ng L-1 for Cd(II) and 93 ng L-1 for Pb(II) with a 10 min preconcentration. The results exhibited that GC/NA-PSS/BiFE can be a reproducible and robust toot for monitor of trace metals by ASV rapidly and environmentally friendly, even in the presence of surface-active compounds.

Studies of interaction between iron (III) and intermediates of synthetic neuromelanin by means of cyclic voltammetry of Fe(CN)(3-)(6) and dopamine

Neuromelanin is a complex polymer pigment found primarily in the dopaminergic neurons of the human substantia nigra, whose composition is complex including production of dopamine auto-oxidation, glutathione and a variety of amino acid. Neuromelanin forms stable complex with iron (111). We observed that 5,6-dihydroxyindole and its ramification possessed strong ability of chelating iron (111), and they are the production of dopamine auto-oxidation under physiological pH condition. In the present Of L-Cysteine, the relative yields of electrochemical oxidation of dopamine also had strong ability of chelating iron (111). The experimental results suggest that 5,6-dihydroxyindole and 5-S-cysteineldopamine play important roles in the process of synthetic neuromelanin chelating iron (111).

Cyclic voltammetry for predicting oxidation process in heterogeneous catalysis

Catalytic reactions with different oxidation process were investigated and correlated to the electrochemical properties of the catalysts. The activity of suprafacial reaction is closely related to the area of redox peak, while that of the intrafacial one is to the match of redox potentials. Accordingly, it is supposed that cyclic voltammetry (CV) measurement could be a means for predicting the oxidation process in heterogeneous catalysis.

Assembly of multilayer films containing iron(III)- substituted Dawson-type heteropolyanions and its electrocatalytic properties: cyclic voltammetry, electrochemical impedance spectroscopy and UV-Vis spectrometry

Ultrathin multilayer films have been prepared by means of alternate adsorption of iron(Ill)-substituted heteropolytungstate anions and a cationic redox polymer on the 4-aminobenzoic acid modified glassy carbon electrode surface based on electrostatic layer-by-layer assembly. Cyclic voltammetry, electrochemical impedance spectroscopy and UV-Vis absorption spectrometry have been used to easily monitor the uniformity of thus-formed multilayer films. Especially, the electrochemical impedance spectroscopy is successfully used to monitor the multilayer deposition processes and is a very useful technique in the characterization of multilayer films because it provides valuable information about the interfacial impedance features. All these results reveal regular film growth with each layer adsorption. The resulting multilayer films can effectively catalyze the reduction of H2O2,NO2- and BrO3-.

Probing UPD-induced surface atomic rearrangement of polycrystalline gold nanofilms with surface plasmon resonance spectroscopy and cyclic voltammetry

Silver underpotential deposition (UPD)-induced surface atomic rearrangement of polycrystalline gold nanofilms was probed with use of surface plasmon resonance spectroscopy (SPRs) as a novel probe tool in combination with cyclic voltammetry. Interestingly, upon repetitive electrochemical UPD and stripping of Ag, the surface structure of the resulting bare Au film is rearranged due to strong adatom-substrate interactions, which causes a large angle shift of SPR R-theta curves, in a good linear relationship with the number of UPDs, to a lower SPR angle. The n, K values of the surfacial Au monolayers before and after the repetitive Ag UPD and stripping for 27 times are found to be 0.133, 3.60 and 0.565, 9.39, respectively, corresponding to the huge shift of 1.61degrees to the left of the SPR minima. Cyclic voltammetry experiments in 0.10 M H2SO4 are carried out before and after the UPD treatment to examine the quality of the whole electrode surface and confirmed this change. To correlate the angle change in SPRs with the profile change in the cyclic voltammogram, the UPD treatment was also performed on a Au(111) textured thin film. It was therefore confirmed that the resonance position of the SPR spectrum is very sensitive to the surface crystallographic orientation of the bare Au substrates. Some surface atomic rearrangement can cause a pronounced SPR angle shift.

Study of the interaction between lanthanide ions and a supported bilayer lipid membrane by cyclic voltammetry and ac impedance

The interaction of lanthanide ions with a supported bilayer lipid (1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine) membrane (sBLM) was investigated by cyclic voltammetry and ac impedance spectroscopy in this paper, Lanthanide can affect the conformation of the supported bilayer lipid membrane and cause pore formation. Through the pores, Fe(CN)(6)(3) (4) can reach the electrode surface and show its redox behaviour. Furthermore the redox currents or Fe(CN)(6)(3) (4) increased with increasing concentration of lanthanides and leveled off at 1.2 muM for Eu3+. The interaction ability of three lanthanides with sBLM follows the sequence: Eu3+ > Tb3+ > La3+.