Interaction between Eu-phenylalanine and DNA Using Cyclic Voltammetry and UV Spectroscopy

The interaction between DNA and the Eu(Phe) 3+ 3 complex ion has been studied by means of cyclic voltammetry and differential UV spectroscopy The results depicted an obvious decrease of peak current in CV plot after the reaction between the two species studied The observed peak potential separation was increased but the diffusion coefficient of Eu complex ion was decreased Hypochromicity was observed at 226 and 258 nm after the predicted interaction of them A preliminary interpretation is proposed for discussion

Cyclic Voltammetry Determination of Epinephrine with a Nano-gold Modified Glassy Carbon Electrode in the Presence of High Concentration Ascorbic Acid

Nano-gold (NG) modified glassy carbon electrodes (GCEs) were used for determination of epinephrine (EP) in the presence of high concentration ascorbic acid (AA) by cyclic voltammetry (CV). This modified electrode can not only catalytically oxidize EP and AA, but also separate the catalytic peak potentials of EP and AA by about 183.5 mV. In pH = 7.0 ogisogate byffer solution, the linear range of epinephrine was 5 106 ~ 1 ?10-4 mol/L.

Determination of Metamizole Sodium by Cyclic Voltammetry Under Microwave Activation

Microwave radiation was applied to the detection of metamizole sodium by cyclic voltammetry. The electrochemical characteristics of metamizole sodium were studied by cyclic voltammetry at GC electrode under microwave radiation and a considerable current enhancement was observed for metamizole sodium in aqueous 0.05 mol/L H2SO4. Under the optional conditions, metamizole sodium was determined in the absence and presence of microwave activation. In the absence of microwave activation cyclic voltammogram of metamizole sodium shows good linear relationship in a concentration range of 8.0×10^-5-1.0×10^-3 mol/L in aqueous 0.05 mol/L H2SO4 with a detection limit of 6.75× 10^-6 mol/L（S/N=3） and the equation of linear regression is Ip=12.973c-0.1905（R^2=0.9996, n=6）; in the presence of 80 W microwave activation cyclic voltammogram of metamizole sodiumin shows good linear relationship in a concentration range of 4.0× 10^-5-1.0×10^-3 mol/L in aqueous 0.05 mol/L H2SO4 with a detection limit of 4,41 × 10^-6 mol/L（S/N=3） and the equation of linear regression is Ip=25.107c-0.1193（R^2=0.9973, n=7）. The current in the presence of 80 W microwave activation increases to about 2 orders of magnitude compared with that in the absence of microwave activation. The proposed method in the presence of microwave activation showed high selectivity and sensitivity, and the sampling of the disposal method is simple. The method was verified by the determination of Metamizole Sodium tablet with satisfactory results.

Preparation and Electrochemical Application of Praseodymium Modified TiO2-NTs/SnO2-Sb Anode by Cyclic Voltammetry Method

A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltarnmetry （CV）. The methyl orange （MO）aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs substrate was synthesized by an electrochemical method to obtain large specific surface area and high space utilization. The phase structure, electrode surface morphology and electrochemical properties of electrodes were characterized by XRD, SEM and electrochemical technology, respectively. The results showed that praseo- dymium oxide was successfully doped into the SnOz-Sb film by CV method. Due to the doped Pr, the oxygen evo- lution potential increased from 2.25 V to 2.40 V. The degradation of MO was investigated by UV-vis. The Ct/C0（φ） was studied as a function to obtain the optimal parameters, such as the amount of doped Pr, current density and initial dye concentration. In addition, the degradation process followed pseudo-first-order reaction kinetics and the rate constant was 0.099 3 min-1. The result indicated that the introduction of Pr reduced the formation of oxygen vacancies or enhanced the formation of adsorbed hydroxyl radical groups on the surface, thus leading to better activity and stability.

Cyclic voltammetry studies on 4 V and 5 V plateaus of non-stoichiometric spinel Li_(1+x)Mn_(2-y)O_4

Li1+xMn2?yO4 spinels with various Li/Mn ratios were synthesized by a solid-state reaction. By X-ray diffraction analysis, Li2MnO3 was detected as a second phase with increasing the Li/Mn ratio; and the role of Li2MnO3 in Li1+xMn2-yO4 spinel was discussed. A slow scanning cyclic voltammetry(CV) at the rate of 0.1 mV/s was adopted to characterize the evolutions of 4 V and 5 V plateaus of Li1+xMn2-yO4 spinels. An additional Li+ insertion in 4 V region was observed in both Li-lack and Li-rich spinels at 3.95 V, which is different from the general Li+ insertion with weak Li-Li interaction and strong Li-Li interaction; and this plateau disappeared in the subsequent cycles. The 4.4 V/3.8 V plateaus correspondent to Li+ insertion and extraction of Li2MnO3 were discussed, and these plateaus have a high reversibility with cycling. The 5 V plateau was found only in the Li-rich samples, and this plateau has a tendency to emerge at higher voltage region with increasing Li/Mn ratio.

Study on Mechanism of Electrodeposition of Y(Ⅲ) in Molten LiF-YF_3-Y_2O_3 by Cyclic Voltammetry

The mechanism of the cathodic process of Y(Ⅲ) on platinum and molybdenum electrode in molten LiF YF 3 Y 2O 3 was investigated by means of cyclic voltammetry. The number of electron transferred was calculated. The results show that the electrochemical reduction of Y(Ⅲ) is a reversible one step three electrons reaction and the cathodic process is diffusion controlled. The reductive product easily forms the intermetallic compounds with the platinum electrode, but it is pure yttrium on the molybdenum electrode.

Studies on the Nucleophilicity and Scavenge of Superoxide Ion by Cyclic Voltammetry

Superoxide ion was generated by the electrochemical reduction of oxygen at a platinum electrode in dimethylsulphoxide (DMSO). This work was focused on the nucleophilicity and scavenge of electrogenerated\|superoxide ion by cyclic voltammetry. The nucleophilic displacement reactions of superoxide ion with ethyl acetate and diethyl adipate were discussed and the reason for remarkable influence of diethyl adipate was elucidated. The scavenging activity of ascorbic acid was evaluated and the result allowed the conclusion that the scavenging ability of ascorbic acid is much lower in DMSO than in aqueous phase. UV\|spectrum of electrogenerated superoxide ion in DMSO exhibited a single absorption band with λ max at 275 nm, which certified further that the method of electrogeneration was reliable and superoxide ion was stable in DMSO.

Assessment of Defects and Collapsed Sites in Self-Assembled Alkanethiol Monolayer on Gold by Cyclic Voltammetry and A.C.Impedance

Self-assembly of octadecyl mercaptan on gold was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy (EIS). Results of CV experiments show thatthere are no structUral defects exposed directly to the redox couple in solution, but EISexperiments indicate that collapsed sites exist in the monolayer. A method to estimate the degree ofdisorder in the Au/thiol monolayer surface is proposed by using admittance plane plot.

Preparation and Cyclic Voltammetry Characterization Of Cu-dipyridyl Imprinted Polymer

Polymer capable of specific binding to Cu-dipyridyl complex was prepared by molecular imprinting technology. The binding specificity of the polymer to the template (Cu-dipyridyl complex) was investigated by cyclic voltametric scanning using the carbon paste electrode modified by polymer particles in phosphate buffer solution. Factors that influence rebinding of the imprinted polymer were explored. The result demonstrated that the cyclic voltammetry was an efficient approach to explore interactions between template and imprinted polymers.

Ultrafast cyclic voltammetry with asymmetrical potential scan

Based on the perfect ohmic drop compensation by online electronic positive feedback, ultrafast cyclic voltammetry with asymmetrical potential scan is achieved for the first time, with the reduction of anthracene acting as the test system. Compared with the traditional cyclic voltammetry utilizing symmetrical triangular waveform as the excitation one, the new method allows a simpler approach to mechanistic analysis of ultrafast chemical reactions coupled with a charge transfer. And perhaps more important, it also provides a way to eliminate the interference of the adsorbed product in dynamic monitoring. 2007 Zhi Yong Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Utilization of Special Potential Scan Programs for Cyclic Voltammetric Development of Different Nickel Oxide-Hydroxide Species on Ni Based Electrodes

Special potential scan programs were designed for cyclic voltammetric development of β-NiOOH or γ-NiOOH/ β-NiOOH mixtures on the surface of nickel or nickel-chromium (80:20) alloy electrodes in NaOH 0.10 M. The pro- grams consisted on changing the anodic or cathodic switching limit to facilitate the chemical reactions taking place ei- ther between Ni(II) hydroxides or between Ni(III) oxides-hydroxides. The electrochemical charge density under the oxidative wave, observed at Ni or Ni-Cr electrode surfaces at approximately 0.48 V (vs SCE), remained almost con- stant with the number of cv cycles after approximately 600 cv cycles at 0.050 V/s. Thus, it can be suggested that a stable proportion of Ni(II)/Ni(III) oxides-hydroxides was obtained on the electrode surfaces. The relative amounts of β-NiOOH or γ-NiOOH species were calculated from the electrochemical charges under their reduction waves in the voltammetric experiments. Higher charge densities were always obtained with Ni-Cr alloy electrodes as compared to pure Ni electrodes. Linear relationships were obtained in our study on the dependence of the oxidative peak current with the square root of the scan rate at a scan rate range between 0.01 V/s and 0.16 V/s.

Evaluating the Stability of Active Manganese Sites During Electrochemical Reactions by Cyclic Voltammetry

Manganese oxides are a promising class of electrocatalysts for renewable energy devices,such as fuel cells.Mn(Ⅲ) ions with e_(g) electron filling of-1 are the active sites for manganese-based electrocatalysts.However,Mn(Ⅲ) sites may be disproportionated during electrochemical reactions,thus reducing the number of Mn(Ⅲ) active sites and decreasing the catalytic activity of manganese oxides.In this work,we developed a facile cyclic voltammetry method to monitor the evolution of Mn(Ⅲ) sites on a series of manganese oxides under "working" conditions.We proposed a descriptor S_(Mn(Ⅲ)) to describe the stability of Mn(Ⅲ).Our simulated and experimental results show that the higher is S_(Mn(Ⅲ)),the higher the active Mn(Ⅲ)density,and the higher the electrocatalytic activity of the manganese oxide electrocatalyst.

A COMPARISON OF THE DETERMINATION OF STABILITY CONSTANTS OF COMPLEXES OF Cd(Ⅱ)WITH AMINO ACIDS AND SIMPLE PEPTIDES USING MICRO—pH—METRIC TITRATIONS AND CYCLIC VOLTAMMETRY

This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of convolution—deconvolution cyclic voltammetry at 25℃ and I=0.10 mol· dm^(-3)(KNO_3).Stability constants were calculated from pH—metric data using the SUPERQUAD com- puter program and cyclic voltammograms were collected,stored and manipulated using the EG and G CONDECON 300 software.A considerably larger ligand:metal ratio(e,g.50:1)was possible using voltammetry.Evaluation of results from the two techniques suggests that stability constants for the species[CdL_2]and[CdL_3]are reliable when calculated fromvoltammetry while those for[CdL]are more reliable when determined by pH-metric titration.

Analysis of Bacterial Cellulose/Ionic Liquid MWCNTs via Cyclic Voltammetry

Cyclic voltammetry based on an electrochemical technique is one of the current methods that measure the developments of the electrochemical properties in biomaterial samples under conditions. Biomaterial structure was changed by conductive material while these materials caused a connective network in whole of them and was able to transfer electrons inside of biomaterials. These changes in physical and chemical properties are investigated by analysis tools such as cyclic voltammetry (CV), X-radiation (XRF) and Ultraviolet-visible spectroscopy (UV-Vis). Bacterial cellulose is biodegradable, biosynthesis of A. xylinum which is a three-dimensional nano-network structure with a distinct tunnel and pore structure. In this study, the composite process produced electrically conducting bacterial cellulose pellicles containing well-dispersed and embedded multi-walled carbon nanotubes (MWCNTs) Ionic liquids (ILs), as observed in cyclic voltammetry (CV). For this purpose, we used a special tool, called OriginLab which is an industry-leading scientific graphing and data analysis software. The cyclic voltammetry graph presents the behavior of this composite which consists of a relationship between CNT dispersion, conductivity rate and changes in bacterial cellulose structure. The electrical conductivity of the cellulose/MWCNT composite was found different with respect to CNT dispersion. It was found that the incorporation process was a useful method not only for dispersing MWCNTs-ILs in an ultrafine fibrous network structure, but also for enhancing the electrical conductivity of the polymeric membranes.

Electrochemical behavior and cyclic fading mechanism of LiNi_(0.5) Mn_(0.5) O_2 electrode in LiNO_3 electrolyte

Electrochemical behavior of layered LiNi0.5Mn0.5O2 in LiNO3 aqueous solution and its cyclic fading mechanism in electrolytes with different pH values were investigated. CV results show that LiNi0.5Mn0.5O2 has good electrochemical reversible behaviors in 5 mol/L LiNO3 solution. Meanwhile, the electrode in 5 mol/L LiNO3 with pH value of 12 demonstrates the best electrochemical stability. Based on the electrochemical impedance spectroscopy （EIS）, X-ray diffraction （XRD） and scanning electron microscopy （SEM） results, it is proposed that suppressed charge-transfer resistance is the major reason, which is probably ascribed to the more stable electrode surface and less structure change.

Sensitive Voltammetric Determination of Captopril Using a Carbon Paste Electrode Modified with Nano-TiO_2/Ferrocene Carboxylic Acid

A carbon paste electrode (CPE) modified with ferrocene carboxylic acid (FcCA) and TiO2 nanoparticles was constructed by incorporating TiO2 nanoparticles and ferrocene carboxylic acid into the carbon paste matrix. The electrochemical behavior of captopril (CAP) at the surface of the modified electrode was investigated using electroanalytical methods. The modified electrode showed excellent electrocatalytic activity for the oxidation of CAP in aqueous solutions at physiological pH values. Cyclic voltammetric curves showed that the oxidation of CAP at the surface of the modified electrode reduced its overpotential by more than 290 mV. The modified electrode was used for detecting captopril using cyclic voltammetry and square wave voltammetry techniques. A calibration curve in the range of 0.03 to 2400 μmol/L was obtained that had a detection limit of 0.0096 μmol/L (3?) under the optimized conditions. The modified electrode was successfully used for the determination of captopril in pharmaceutical and biological samples.

Studies on the Voltammetric Determination of Clenbuterol at One-touch Immunochips

A novel immunosensor for determination of clenbuterol was described in this paper. Horseradish peroxidase (HRP) and Monoclonal antibody against clenbuterol was covalently immobilized onto the cellulose acetate membrane which was used as one-touch immunochips. After 20 min of competitive reaction of clenbuterol in samples against glucose oxidase-conjugated clenbuterol (CLB-GOD) with anti-clenbuteol antibody immobilized on the membrane, the one-touch transducer was fixed on the Nafion - ferrocene modified glass-carbon electrode (GCE, working electrode) by “O” ring. The increased current changes (ΔI) were recorded for the quantitative determination of clenbuterol by derivative cyclic voltammetry. Experimental results showed that a very effective system for electron transmission had been established using dual-enzyme system and Nafion-ferrocene modified GCE. Quantitative analysis of clenbuterol could be easily performed on this kind of immunosensor, which showed the advantage of time-saving and high sensitivity (The detecting limit of this kind of immunosensor can be down to 100 ng/L). In addition, other conditions affecting the electrochemical response were also discussed in detail.

Synthesis, Structure and Electrochemistry of Macrocyclic 1,1'-Bis(1,3-phenyleneoxyacetylpyrazoyl)ferrocene

1,1＇-Diacetoacetylferrocene 1 reacted with phenylene-1,3-dioxyactyl hydrazine 2 in absolute ethanol to give the macrocyclic ferrocenyl dipyrazole compound in moderate yield. Determined by X-ray structure analysis, it crystallizes in monoclinic system, space group P21/c with a = 13.7509（4）, b = 8.1277（2）, c = 21.7472（6） A, β = 103.1030（10）°, V = 2367.25（11） A^3, Z = 4, Dc = 1.505 g/cm^3, R = 0.0353 and wR = 0.0811. The electrochemical studies reveal that redox of Fe^＋/Fe in ferrocene is a reversible one-electron process.

Voltammetric Studies of the Interaction of Tris (1,10-phenanthroline) Cobalt (III) with Bovine Serum Albumin

The voltammetric methods were used to prove the interaction of metal complex Co(phen)(3)(3+) with bovine serum albumin (BSA). The interaction of BSA with Co(phen)(3)(3+) molecules using BSA-modified electrode is described. Information of the binding ratio and interaction mode can be obtained from their electrochemical behavior and electrochemical data. Furthermore, attenuated total reflection infrared experiment was performed to prove the interaction between complexes and BSA.