bluuebunny/crossref_metadata_2025_split huggingface dataset:
The electrochemical behavior of eastman AQ/meldola blue‐coated microelectrodes
Authors: Tian Min , Dong Shaojun 
Published: May 2005

AbstractEastman‐AQ 55D was coated onto a carbon fiber microelectrode surface, and the resulting modified electrodes exhibited high stability. Substantial improvement in the stability was observed as a result of good adhesion and the strong binding of large hydrophobic cations of Eastman AQ 55D. The electrode reaction of meldola blue bound in the polymer film showed a reversible, one‐electron transfer process. The effects of solution pH and influence of supporting electrolyte on the modified carbon fiber microelectrode are discussed. The diffusion coefficient of meldola blue in the AQ polymer film determined by chronoamperometry is 2.3 × 10−8 cm2 s−1, and the heterogeneous rate constant of meldola blue at the AQ polymer film/electrode determined by normal pulse voltammetry is 3.97 × 10−3 cm s−1.
Redox reaction of myoglobin at a benzimidazole‐modified silver electrode
Authors: Li Genxi , Fang Huiqun , Qian Yiqun , Chen Hongyuan 
Published: May 2005

AbstractBenzimidazole could be attached to a silver electrode by a covalent bonding method to give a high stable chemically modified electrode. Not only was the modified electrode electroactive, myoglobin could also undergo redox reactions at the surface of the electrode. In 0.20 mol/L NaAc‐HAc buffer (pH 5.5), the benzimidazole modified electrode gave a pair of redox waves with a cathodic peak potential Epc of 0.10V and an anodic peak potential Epa of 0.25 V. On addition of myoglobin to the buffer, the peaks all increased due to the redox processes of the protein. In addition, comparison studies of the purified protein with the commercial sample revealed that myoglobin could still give electrode response even though it had not been previously purified. Therefore, benzimidazole modified silver electrode might be very attractive for the electrochemical studies of myoglobin.
Amperometric flow injection analysis of organic thiols and proteins
Authors: Hidayat Achmad , Hibbert D. Brynn , Alexander Peter W. 
Published: May 2005

AbstractThe amperometric determination of thiols by injection into a mercury carrier stream is shown to be a sensitive method when using a tungsten wire as the working electrode in a three‐electrode flow cell. Hg2+ gives sharp peaks when injected into phosphate buffer at pH 3.1 at an operating voltage of −0.24V (against a Ag/AgCl reference electrode). Hg2+ was determined in the range 0.43 to 25.0 μM with linear response. Injection of cysteine into the mercury carrier causes a decrease in the cathodic current, and sharp flow injection peaks are observed with a peak width of approximately 60 s. Optimization of various parameters was performed, including buffer effects, mercury concentration, injection volume, and the effects of various cations and anions on the response were determined. Linear calibrations in the range 0.25 μM to 100 μM for cysteine and 1.3 to 1000 ng for the other thiols glutathione, thiourea, albumin, and DNA were found. The responses to cysteine and thiourea were most sensitive, and interference from silver and iodate was observed at concentrations in excess of the thiols. The method may be used as a rapid means of detecting thiols in various samples and as an HPLC detection method.
Characterization of blend membranes of regenerated silk fibroin and PVA for immobilizing glucose oxidase and its application to a first generation of glucose sensors
Authors: Qian Jianghong , Liu Haiying , Liu Yongcheng , Yu Tongyin , Deng Jiaqi 
Published: May 2005

AbstractThe structure, water absorbability and mechanical properties of the blend membranes of regenerated silk fibroin and poly(vinyl alcohol) were investigated. IR spectra showed regenerated silk fibroin in the blend membranes exists chiefly in the silk I structure after ethanol treatment. An amperometric biosensor for glucose was constructed by coupling glucose oxidase in the blend membrane of regenerated silk fibroin and PVA with platinum electrode. Its experimental parameters such as pH, temperature and applied potential were optimized. It determined glucose in less than 25 s with good reproducibility and exhibited high storage and operational stability.
Variability of the slopes of standard addition plots in the analysis of copper in seawater by anodic stripping voltammetry
Authors: Sánchez‐Misiego Antonio , Carra Rosa García‐Moncó , Zirino Alberto 
Published: May 2005

AbstractCopper in seawater was analyzed with a ‘hybrid’ mercury film‐glassy carbon electrode using linear sweep, square wave and differential pulse anodic stripping voltammetry. The analyses were made in HCl (pH 2) and ethylenediamine (EN)‐spiked seawater (9 < pH < 10), with and without purging the sample of dissolved oxygen. The relative slopes of the standard addition plots were used to determine the effect of mode and media alteration on the results. Square‐wave voltammetry in EN‐altered seawater, without oxygen purging, was found to be not only the most practical technique, but also highly sensitive. The ‘chemistry’ of the oxidation reaction during the stripping step was found to affect the experimental results markedly. For this reason, the peak current is an experimentally dependent measure of the ion flux, both, into and out of the electrode.
Application of a chelite P modified carbon paste electrode to copper analysis and speciation
Authors: Agraz Raquel , De Miguel Javier , Sevilla Maria‐Teresa , Hernandez Lucas 
Published: May 2005

AbstractA carbon paste electrode modified with the commercial resin Chelite P, containing amino‐phosphonic groups, was used in the determination and speciation of copper. Copper analysis was performed with cyclic voltammetry and differential pulse voltammetry, allowing copper determination in the μg/L level. A detection limit of 1.9 μg/L (3α) was found for a 10 min preconcentration. Interferences from other ions and organic substances were examined. For speciation purposes, a ligand competition methodology was used and different model ligands in solution were tested. Copper complexes were characterized as a function of their thermodynamic and kinetics properties. Results were compared with those obtained employing a strong chelating resin (containing iminodiacetic acid) as electrode modifier. The method was applied to a water sample from the Jarama river in Madrid, where copper was mainly present as strong low‐dissociating complexes.
Programmed‐potential voltammetric determination of nitrate at a static mercury drop electrode in natural waters and soil extracts
Authors: Markušová Kveta , Kohútová Lýdia , Dzurov Ján 
Published: May 2005

AbstractLinear‐scan or differential pulse voltammetry with electrode surface modified at a mercury drop presweep potential of −1.8 V is used for the determination of nitrate in the presence of trivalent cations. The method has been applied to the determination of nitrate in drinking and riverwaters, and in soil extracts with determination limit of 0.3 μ M (20 μg L−1).
Local anesthetics measured by lipophilic β‐cyclodextrin‐based ion‐selective electrodes
Authors: Kataky Ritu , Palmer Simon 
Published: May 2005

Abstract2,3,6‐Trioctyl and 2,6‐didodecyl‐β‐cyclodextrins have been incorporated in ion‐selective electrodes as neutral ionophores for the detection of the local anesthetics procaine, prilocaine, lidocaine and bupivacaine hydrochlorides. Nernstian response and excellent limits of detection were observed (−log [C]≥5.0). Interference from ‘serum’ levels of sodium, potassium and calcium (150.0 mmol dm−3 Na+, 1.26 mmol dm−3 Ca2+ 4.30 mmol dm−3 K+ ), was negligible (−log K,) (overall)≥4.0). The major organic interferents were molecules of similar size and structure which caused reduced slope and drift in baseline potentials at 10 mmol dm−3 levels of concentrations. However, the interferences were substantially reduced when the interferent concentration was reduced by a factor of 10. Nernstian response was maintained in the presence of bovine serum albumin (BSA), serum (HS) and aI acid glycoprotein (AAG). A polyurethane, (Tecoflex SG80) membrane matrix was more biocompatible when compared to PVC as evidenced by lower E0 (internal) shifts with the former.
A comparative study of some phenoxazine and phenothiazine modified carbon paste electrodes for ethanol determination
Authors: Lobo M. Jesús , Miranda Arturo J. , Tuñón Paulino 
Published: May 2005

AbstractAn amperometric ethanol electrode is described based on carbon paste modified with alcohol dehydrogenase (ADH) and a mediator. The possibility of coupling this enzymatic system with some commercially available phenoxazines [Meldola Blue (MB), Nile Blue (NB) and Brilliant Cresyl Blue (BCB)] and phenothiazines [Toluidine Blue 0 (TBO)], that allows the electrocatalytic oxidation of NADH, was investigated. Different strategies of mediator immobilization in the carbon paste were compared. The most suitable immobilization technique was the coverage of the modified carbon paste surface with a dialysis membrane and the best electrocatalytic structure was the phenothiazine TBO. The TBO(10%)‐ADH(5%)‐modified carbon paste electrode shows steady state signals for ethanol within 30 s. The influence of various experimental conditions was explored for optimum analytical performance. Amperometric detection of ethanol at an applied potential of 50mV (Ag/AgCl) gives linear responses over the concentration range of 10–l0μM, with a detection limit of 5 × 10−6M. The modified electrode was applied to the determination of ethanol in wine.
Flow‐type cyanide sensor using an immobilized microorganism
Authors: Ikebukuro Kazunori , Honda Masahiro , Nakanishi Keijiro , Nomura Yoko , Masuda Yuzo , Yokoyama Kenji , Yamauchi Yoshihiro , Karube Isao 
Published: May 2005

AbstractA flow system for cyanide detection using Saccharomyces cerevisiae is described. This sensor system consists of two oxygen electrodes and immobilized S. cerevisiae whose respiration activity is measured by the oxygen electrodes. Since cyanide inhibits S. cerevisiae's respiration, it can be detected by measuring this inhibition. Two types of systems were constructed, characterized and compared. One is a membrane‐type flow system in which S. cerevisiae was immobilized onto a cellulose membrane. The other is a reactor‐type flow system in which S. cerevisiae was immobilized onto the glass beads. The sensor response was examined in the range from 0 to 15μM. The reactor‐type sensor system displayed lower detection limit (0.15 μM) and better stability (16 days).
Alkaline phosphatase assay using a redox procationic labeled substrate and a renewable Nafion‐loaded carbon paste electrode
Authors: Rapicault Stéphane , Limoges Benoît , Degrand Chantal 
Published: May 2005

AbstractThe indirect electrochemical determination of alkaline phosphatase was achieved with a detection limit of 2 Ul−1 at a fresh surface of a renewable Nafion‐loaded carbon paste electrode, without preconditioning. [N‐ferrocenoyl]‐4‐aminophenyl phosphate was used as substrate and the enzyme reaction proceeded for 15 min in Tris buffer at pH 9.0. [N‐ferrocenoyl]‐4‐aminophenol was thus generated, which was further preconcentrated at the modified carbon paste electrode during a 5 min accumulation step in neutral medium. A potential of 0.35 V was applied during this step, and so the substituted phenol was irreversibly entrapped as a ferrocenium salt within Nafion before being detected by square wave voltammetry.
Trace measurements of insulin by potentiometric stripping analysis at carbon paste electrodes
Authors: Wang Joseph , Rivas Gustavo , Cai Xiaohua , Chicharro Manuel , Farias Percio A. M. , Palecek Emil 
Published: May 2005

AbstractA potentiometric stripping method for trace measurements of insulin at carbon paste electrodes is described. The method is based on the controlled adsorptive accumulation of this polypeptide hormone at the anodically pretreated carbon surface followed by constant‐current chronopotentiometric measurements of the surface species. A well‐defined peak, associated with the oxidation of the tyrosine residues, is observed over the flat baseline of the potentiometric stripping operation. Variables of the pretreatment and measurement steps are optimized to offer a detection limit of 2 × 10−9M after 5 min preconcentration. Excess of nunierous potential interferences does not influence the response observed after transferring the electrode (with the accumulated insulin) to a blank electrolyte solution. A similar protocol is described for trace measurements of the protein myoglobin.
Ohmic distortion of mass transport and of current–voltage curves at a channel electrode
Authors: Cales Barry A. , Compton Richard G. , Larsen Jane P. , Anthony Spackman R. 
Published: May 2005

AbstractThe distortion caused by the ohmic resistance of the solution in a channel electrode experiment has been calculated by combining a three‐dimensional finite element approach based on a resistor network, solved by the SPICE program, in an iterative procedure with the backward‐implicit finite difference method, for the case of a reversible 1‐electron reduction. By this means, the current distribution over the electrode may be calculated taking into account not only the nonuniform potential distribution imposed by the electrolyte resistance but also the alteration to mass transport induced by the potential distribution. The potential‐dependent variation in Tafel slope introduced by the ohmic distortion is calculated and is shown to be in close agreement with experimental data obtained from the reversible one‐electron reduction of p‐chloranil, allowing the practical current range for experimental measurements to be assessed and if necessary extended. The three‐dimensional SPICE simulation has also been applied to study the effect of reducing the electrode width to a small fraction of the channel width, when significant current flow to the sides of the electrode will occur.
Rotating disk ion selective electrodes
Authors: Cassidy John , Mullen David , Casey Karen , Cullen Patrick 
Published: May 2005

AbstractA simulation was undertaken to predict the transient potential response following a concentration step at a rotating disk electrode comprised of an ion selective layer. A basis for this simulation was that the potential response would be independent of rotation rate since the diffusion layer is larger than the double layer at the electrode. In practice it was found that the potential response does vary with rotation rate. The response was such that the apparent concentration of the analyte in solution decreased with increased rotation rate. The reason for this behavior is due to the disruption of the double layer at the electrode surface by convection.
Determination of carbendazim with a graphite electrode modified with silicone OV‐17
Authors: Hernandez Pedro , Ballesteros Yolanda , Galan Fernando , Hernandez Lucas 
Published: May 2005

AbstractThe cyclic voltammetric characterization of a graphite electrode modified with silicone OV‐17 was carried out on a solution of ferroine. Afterwards, the electrochemical behavior of carbendazim following its accumulation on the electrode surface, was studied. Best conditions for its determination in the preconcentration and measurement steps were established. The method, with a relative error of 3.7% and a determination limit of 9.1 ng/mL, was applied for wine, apple and cultivated soil samples.
Electrochemical determination of carboplatin in serum using a DNA‐modified glassy carbon electrode
Authors: Brett Ana Maria Oliveira , Serrano Sílvia H. P. , Macedo Tice A. , Raimundo Dulce , Helena Marques M. , La‐Scalea Mauro A. 
Published: May 2005

AbstractAn electrochemical method for the determination of the anticancer platinum drug carboplatin using a DNA‐modified electrode was developed. This electrode was successfully used for the electrochemical determination of carboplatin in serum samples of patients with ovarian cancer undergoing treatment. The electrochemical results clearly demonstrated that, for low concentrations, carboplatin interacts preferentially with adenine rather than guanine groups in the DNA and they can contribute to clarifying the mechanisms of interaction of platinum anticancer drugs with DNA. The pharmacokinetics corresponding to the administration of the drug was followed electrochemically and the detection limit in serum samples was 5.7 × 10 −6M. Due to a similar mechanism of reaction with DNA other platinum anticancer drugs can be determined by this method.
Fast adsorptive stripping voltammetry of iron in oxygenated seawater
Authors: Gelado‐Caballero María D. , Hernández‐Brito José J. , Herrera‐Melián José A. , Collado‐Sanchez Cayetano , Pérez‐Peña Jesús 
Published: May 2005

AbstractA fast adsorptive stripping voltammetric procedure for the determination of ultratrace amounts of iron in unpurged oceanic waters is reported. The method is based on that developed by van den Berg et al. [l]. It was modified to increase the sensitivity, to measure in the presence of oxygen and to reduce drastically the analysis time at the ultratrace level (pM). The scan rate, pH and concentrations of reagents were optimized to avoid interferences using background correction. The catalytic effect of the hydrogen peroxide was not found using high scan rate. The instability of the peak was related to colloidal iron. Acidified or heated samples showed stable peaks. The method is insensitive to the turbulence of the solution during the scan. The reproducibility (±40 pM) and detection limits (120 pM) of the method were calculated using 60s deposition time and oceanic waters (600pM). The detection limit can be lowered to 70 pM using 3 min accumulation.
Voltammetric detection of phosphate ion binding to β‐amino‐cyclodextrin
Authors: Godínez Luis A. , Lin James , Muñoz Marc , Coleman Anthony W. , Kaifer Angel E. 
Published: May 2005

AbstractThe complexation of phosphate ion by β‐amino‐cyclodextrin (host 1) was detected by voltammetric methods through the competitive displacement of water‐soluble ferrocene derivatives from their complexes with host 1 in neutral aqueous media. The half‐wave potential and the anodic peak current for oxidation of the ferrocene derivative were found to be sensitive to the phosphate concentration throughout a range which is determined, among other factors, by the concentration of host 1 and the binding constant between the selected ferrocene derivative and the β‐amino‐cyclodextrin host.
The reduction of bromate at molybdenum oxide film cathodes
Authors: Bertotti Mauro , Pletcher Derek 
Published: May 2005

AbstractThe catalytic reduction of bromate at vitreous carbon electrodes modified with a molybdenum oxide film at pH 3 has been investigated further. In addition, the reduction has been investigated at lower pH using molybdenum oxide films formed in situ from solutions containing both MoVI and BrO. It is shown that in both systems, the variation of the current for bromate reduction with potential passes through a maximum and, hence, at more negative potentials, the surface is markedly less active for bromate reduction. With MoVI in solution, a recovery in the catalytic activity slowly occurs and this effect has also been investigated.
Reactor type sensor for cyanide using an immobilized microorganism
Authors: Lee Jeong Im , Karube Isao 
Published: May 2005

AbstractA reactor type biosensor using an immobilized bacteria (Pseudomonas fluorescens NCIMB 11764) columm and an oxygen electrode was developed for cyanide. The optimum conditions for the sensor in a flow system (pH 9, 25°C, flow rate 2.5 mg/min) resulted in a response time of less than 5min. A linear relationship was observed between the current decrease and the cyanide concentration over the range of 0.05−1 mg/L. Operating at 25 °C, the sensor was stable up to 30 days. Alginate gel as the immobilized matrix was more suitable than other matrices (agars, polyurethane, porous glass beads, zeolite, chitopearl). Satisfactory results were obtained when the sensor was applied to determine the concentration of cyanide in the river water.
Effect of HY‐zeolites on the performance of tyrosinase‐modified carbon paste electrodes
Authors: Marko‐Varga György , Burestedt Elisabeth , Svensson Carl Johan , Emnéus Jenny , Gorton Lo , Ruzgas Tautgirdas , Lutz Mareike , Unger Klaus K. 
Published: May 2005

AbstractThe dependence of electrode response on additive properties in enzyme‐modified carbon paste was studied. Four different HY‐zeolite powders, dealuminated to different extents and characterized by both Si/Al ratio and hydrophilicity, were used as the carbon paste modifiers. The enzyme tyrosinase used in biosensors for the detection of catechol and other phenolic compounds was chosen as the model system for the construction of a composite carbon paste biosensor incorporating different HY‐zeolites as additives. Tyrosinase was trapped on the HY‐zeolite particles from a buffer solution, dried and mixed with graphite powder and a pasting oil. It was found that by incorporating HY‐zeolites into the carbon paste the heterogeneous reaction rate of catechol redox conversion and the signal response for catechol were increased. In the latter case a higher response was observed for increased hydrophilicity, i.e., decreased Si/Al ratio of the HY‐zeolite. The carbon paste/solution interface is considered to be an aqueous/organic phase and the characteristics of the enzyme‐ modified carbon paste electrode are related to theories, explaining enzymatic catalysis in organic solvents.
Off‐line and on‐line differential pulse anodic stripping voltammetric techniques for the determination of antimony(III) and antimony(V) in zinc plant electrolyte
Authors: Bond Alan M. , Kratsis Steven , Newman O. Michael G. , Pfund B. Valentin 
Published: May 2005

AbstractAntimony, in both its trivalent and pentavalent states may be detrimental to the electrochemical deposition of zinc. Ideally, therefore antimony should be monitored in both oxidation states throughout an electrolytic zinc plant. At hydrochloric acid concentrations ( > 4 M) both antimony(III) and (V) present in zinc plant electrolyte can be reduced at a hanging mercury drop electrode (HMDE) to form an antimony amalgam, Sb(Hg). Consequently a very sensitive analytical signal is obtained for the determination of total antimony by differential pulse anodic stripping voltammetry (DPASV) using a 1:1 mixture of plant electrolyte and concentrated hydrochloric acid. In contrast, at low acid concentrations (0.1 M) predominantly only antimony(III) can be reduced and therefore determined in zinc plant electrolyte by DPASV at a HMDE by use of a 1:1 mixture of plant electrolyte and 0.2 M hydrochloric acid. The antimony(V) concentration is calculated by the method of subtraction of antimony(III) from total antimony. Consequently, simple addition of high and low concentrations of hydrochloric acid to zinc plant electrolyte can be used to provide a suitable electrolyte for both off‐line and on‐line methods for determining the concentration of total antimony, antimony(III) and antimony(V). The method described in this article has been applied to a wide range of zinc electrolyte samples and an on‐stream analyzer technique has been successfully used for several years at the Pasminco Metals‐BHAS electrolytic zinc plant in Port Pirrie, Australia.