bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical and spectroelectrochemical study of copper bleomycin complexes
Authors: Fultz Mary Lou , Durst Richard A. 
Published: May 2005

AbstractThe electrochemical behavior of the copper(II) complex of bleomycin, a glycopeptide antibiotic with antitumor activity, was investigated in several buffer systems using cyclic voltammetry, polarography, coulometry, and spectroelectrochemistry. The copper bleomycin complex exhibited irreversible one‐electron reduction on glassy carbon and mercury electrodes and was electroinactive on platinum, gold, and silver. After the initial reduction process on mercury, the appearance of the Cu(0)/(II) redox couple indicated dissociation of the complex and subsequent reduction of the Cu(I) to the metal. In the presence of excess bleomycin, the Cu(II) reoxidized from the mercury electrode is rapidly complexed and no copper reduction process is observed. On glassy carbon, however, the Cu(I) bleomycin complex is stable and does not undergo further reduction, as demonstrated by spectroelectrochemistry at a reticulated vitreous carbon optically transparent electrode. Consequently, as with many metallo‐organic redox processes, there appear to be several possible electrochemical pathways depending on the pH, the electrode materials, and the experimental time domain.
Determination of ionized and total calcium in white wine using a calcium ion‐selective electrode
Authors: Cardwell Terence J. , Cattrall Robert W. , Mrzljak Robert I. , Sweeney Therese , Robins Lisa M. , Scollary Geoffrey R. 
Published: May 2005

AbstractThe free, or ionized, calcium concentration in white wine was determined using a calcium ion‐selective electrode. Calibration was achieved using a standard curve constructed from calcium standards that matched each wine sample in pH, ionic strength, and ethanol concentration. A more rapid procedure for the determination of the calcium ion activity using aqueous standards was also studied. The effect of dilution on the ratio of free to bound calcium was examined. Using a dilution factor of 10, between 71 and 78% of the total calcium concentration can be sensed by the electrode, the proportion increasing to between 81 and 92% with a dilution factor of 100. The estimation of the total calcium concentration, based on the value obtained from the 10‐fold dilution, is proposed.
Electrochemical detection for capillary electrophoresis
Authors: Curry P. D. , Engstro‐Silverman C. E. , Ewing A. G. 
Published: May 2005

AbstractCapillary electrophoresis and the use of electrochemically based detection schemes for capillary electrophoresis are reviewed. The three different electrochemical methods used in capillary electrophoresis include potentiometric, conductivity, and amperometric detection.
Fundamental studies on fast scan stripping voltammetry with a microelectrode
Authors: Nomura Satoshi , Nozaki Koichi , Okazaki Satoshi 
Published: May 2005

AbstractApplication of rapid‐response voltammetry to stripping analysis was carried out, and novel fast scan stripping voltammetry (FSSV) was developed. A remarkable increase in analytical sensitivity could be attained as a result of the minimization of the background current through the use of an ultramicrodisk electrode (UMDE) and the fast scan rate of 300 V/s. The interference of dissolved oxygen and copper ion were greatly eliminated owing to their slow charge transfer rate. This new type of stripping method also turned out to be a rapid and reliable analytical method.
Relationship between charge transfer resistance and exchange current density of ion transfer at the interface of two immiscible electrolyte solutions
Authors: Horvai G. 
Published: May 2005

AbstractA simple derivation shows the validity of the reciprocal relation between charge transfer resistance and exchange current density. The result is independent of the equation used for estimating the potential difference across the space charge region. Butler‐Volmer kinetics with Frumkin correction or the Ver wey‐Niessen model (i.e. Frumkin correction only) lead to the same result.
Voltammetric studies of nitrofuroxime
Authors: Reddy C. Suresh , Reddy S. Jayarama 
Published: May 2005

AbstractThe electrochemical reduction behavior of nitrofuroxime has been studied using do polarography, cyclic voltammetry, ac polarography, differential pulse polarography, millicoulometry, and controlled potential electrolysis in universal buffers of pH values ranging from 2.0 to 12.0 in DMF/water mixtures. Kinetic parameters such as diffusion coefficient and forward rate constant values are evaluated, and a reduction mechanism is proposed. A differential pulse polarography method is developed for the quantitative determination of nitrofuroxime in pharmaceutical formulations. The method of standard additions is used. The relative standard deviation and correlation coefficient are 1.84% and 0.991, respectively.
Application of ion‐selective electrodes in clinical analysis
Authors: Lewenstam Andrzej , Maj‐Zurawska Magdalena , Hulanicki Adam 
Published: May 2005

AbstractIon‐selective electrodes (ISEs) currently used in clinical analysis are reviewed. The theory of these sensors is outlined. Problems specific for the application of ISEs in clinical analysis are discussed. The prospects for use of new ISEs for clinical purposes are evaluated. More than 50 references are included.
Effect of background charge on estimating diffusion coefficients by chronocoulometry at glassy carbon electrodes
Authors: Sucheta Artur , Rusling James F. 
Published: May 2005

AbstractLarge background charges were observed in single potential‐step chronocoulometry obtained with glassy carbon electrodes. Analyses of uncorrected data gave large errors in diffusion coefficients (D) for vitamin B12 and ferrocyanide, whose electrode reactions are on opposite sides of 0 V (vs. SCE) where different surface redox processes occur. Subtraction of separately measured average background charge yielded values for D in good agreement with those previously reported. The use of the correct model for the electrode reaction was also necessary for accurate estimation of D. Even when the final potential was 350 mV positive of the quasireversible ferrocyanide cyclic voltammetric (CV) oxidation peak, the diffusion model gave poor fits to background subtracted chronocoulometric data and errors in D. This is attributed to formation of films on the electrodes at these potentials, especially at pH 12. However, the slow electron transfer model fit these data quite well, provided an accurate value of D, and also gave rate constants for heterogeneous electron transfer.
Reagentless hydrogen peroxide and glucose sensors based on peroxidase immobilized on graphite electrodes
Authors: Jönsson‐Pettersson Gunilla 
Published: May 2005

AbstractThe electrocatalytic reduction of hydrogen peroxide (H2O2) by horseradish peroxidase (HRP) immobilized on graphite electrodes without the addition of an electron mediator was found to start at + 600 mV vs. Ag/AgCl and the highest current was obtained at about −100 mV. With an applied potential of −50 mV and in the absence of soluble mediator, linear calibration curves for H2O2 were obtained between 0.5 μM and 250 μM and for β‐D‐glucose in air‐saturated solution between 2 μM and 0.5 μM (HRP co‐immobilized with glucose oxidase). Cross‐linking the enzymes with glutaraldehyde and bovine serum albumin was found to increase the stability of the sensors without causing mass transfer resistance within the enzyme layer. The response time was 5 seconds both for H2O2 and for glucose and the sample through put was 150 samples h−1. The glucose measurements were made in 0.1 M phosphate buffer, pH 6, where no interfering from physiological levels of ascorbic acid, uric acid, or paracetamol (acetaminophen) could be detected.
A novel and highly sensitive single‐sweep oscillopolarographic method for the determination of ultratrace amounts of ruthenium
Authors: Zhi‐liang Jiang 
Published: May 2005

AbstractA novel and highly sensitive oscillopolarographic method is described for determining ruthenium as low as 7.9 × 10−11 M, based on its catalysis of the redox reaction between Ce(IV) and As(III). The changes in concentration of As(III) in the reaction is traced by single‐sweep oscillopolarography. The influence of 34 foreign ions is considered. Ruthenium in ore samples was analyzed by the method, and good results were obtained.
Voltammetry of captopril on the hanging mercury drop electrode
Authors: Passamonti Paolo , Ferraro Stefano , Bartocci Vito , Pucciarelli Filippo 
Published: May 2005

AbstractThe electrochemical behavior of 1‐[(2S)‐3‐mercapto‐2‐methyl‐1‐oxopropyl]‐L‐Proline (Captopril) was studied by cyclic voltammetry (CV). The influence of pH on the diffusion waves and the parameters associated with them were studied. The diffusion waves exhibit a quasi‐reversible mechanism at low pH (under pH = 6.5) and an irreversible electron transfer at higher pH values. Product adsorption waves (prepeaks) showing marked reversible behavior were observed and studied only at a pH of 2.20. Various parameters such as electron transfer rate (Ksh), maximum surface excess concentration (Γt), electron transfer coefficient (α), Frumkin's interaction parameter, (g) and diffusion coefficient (Dr) were calculated.
Electroanalysis with electrodes modified by inorganic films
Authors: Cox James A. , Jaworski Robert , Kulesza Pawel J. 
Published: May 2005

AbstractThe electroanalytical utility of electrodes modified with inorganic films is reviewed. Various types of inorganic layers (metal oxides, polynuclear transition metal cyanides, zeolites, metal porphyrins and phthalocyanines) are assessed. Various detection schemes based on these modified surfaces are described in 129 references.
The use of electropolymerization to produce new sensing surfaces: A review emphasizing electrode position of heteroaromatic compounds
Authors: Imisides Mark D. , John Richard , Riley Peter J. , Wallace Gordon G. 
Published: May 2005

AbstractThe synthesis and utilization of electrodes modified with conducting polymers is reviewed. Specific issues evaluated include the various approaches available to produce the required functionality at the electrode surface and the practical considerations to be addressed during synthesis, both in terms of hardware requirements and the chemistry of electropolymerization. The review concludes with a survey of the many applications of polymer‐modified electrodes and includes 112 references.
Potentiometric anion selectivities of polymer membranes doped with indium(III)‐porphyrins
Authors: Park S. B. , Matuszewski W. , Meyerhoff M. E. , Liu Y. H. , Kadish K. M. 
Published: May 2005

AbstractThe potentiometric anion responses of polymeric membranes doped with various indium (III)‐porphyrin structures are examined. The appropriate membranes are prepared by incorporating 1.0 wt % of the In(III)‐porphyrins in plasticized poly(vinyl chloride) films. When such membranes are incorporated within standard ion selective electrode bodies, the resulting electrodes display non‐Hofmeister anion selectivity, with a particularly enhanced and super‐Nernstian response to chloride. Among those porphyrins investigated, membranes doped with chloro(octaethylporphyrinato)indium(III) yield the largest and most reproducible potentiometric anion responses. These same membrane electrodes exhibit negligible response to protons (or hydroxide) in the range of pH 4.5–9.0. When utilized as a flow‐injection detector in conjunction with a protein diluent/buffer stream, the In(III)‐porphyrin based electrodes may be used to determine chloride levels in human serum samples.
The determination of electron transfer parameters for monosubstituted ferrocenes suitable as mediators in amperometric biosensors
Authors: Löffler Uwe , Göpel Wolfgang , Speiser Bernd 
Published: May 2005

AbstractThe quasi‐reversible electron transfer of monosubstituted ferrocenes at a gold electrode in acetonitrile, water, and an aqueous surfactant solution is characterized by formal potentials, diffusion coefficients, heterogeneous electron transfer rate constants, and transfer coefficients. These system parameters are calculated from peak potentials, peak currents, and peak potential differences by means of the multiparameter estimation technique. The results are compared with those of a combined evaluation of rotating disk electrode (rde) and cyclic voltammetric data. The former method can be used even if the rde results are distorted by filming of the electrode. The size of the molecules and, in the case of surfactant addition, the size of micelles containing the ferrocenes is estimated from diffusion coefficients. The electrochemical properties are discussed in view of future applications of these compounds as mediators in amperometric biosensors.
The application of quaternary ammonium ionic polymers to electroanalysis: Part 1. quaternary ammonium ionic polymer membranes for solid‐state, ion‐selective electrodes
Authors: Rocheleau Marie‐Josée , Purdy William C. 
Published: May 2005

AbstractThe preparation, properties, and response characteristics of polymeric ion‐selective membrane electrodes prepared from poly(vinylbenzyl chloride) functionalized with quaternary ammonium groups are described. Notably, a carbon‐support electrode coated with a film of poly(trihexylvinylbenzylammonium thiocyanate) yielded a highly selective Nernstian response to thiocyanate in the concentration range 5 × 10−5−0.1 M. The selectivity of this membrane electrode can be favorably compared with that of conventional thiocyanate ion‐selective electrodes. The use of functionalized polymer membranes with solid‐support electrodes represents an interesting alternative to conventional polymeric membranes.
The application of quaternary ammonium ionic polymers to electroanalysis: Part 2. Voltammetric studies with quaternary ammonium functionalized polymer film‐coated electrodes
Authors: Rocheleau Marie‐Josée , Purdy William C. 
Published: May 2005

AbstractThe application of quaternary ammonium functionalized polymers to voltammetric analysis is described. A glassy carbon electrode coated with a thin film of poly(trihexylvinylbenzylammonium chloride) exhibited attractive permselectivity to uric acid. Typically, this polymer‐modified electrode yielded a linear voltammetric response to uric acid in the concentration range of 1–10 μM. The ion exchange properties of poly(trihexylvinylbenzylammonium chloride) was related to the Gibbs‐Donnan equation. Also, chronoamperometry was used to probe the charge‐transport and response mechanisms within this type of ionic polymer film.
Adsorptive stripping tensammetry of commercially available oxyethylated alcohols: Part 2. Surfactants having C16C18hydrophobe
Authors: Szymanski Andrzej , Lukaszewski Zenon 
Published: May 2005

AbstractThe behavior of oxyethylated straight chain alcohols having the C16Cl8, hydrophobe and 10, 18, 25, 30, and 40 oxyethylene subunits was investigated, The dependences of the peak height on the concentration of surfactant, preconcentration time, and preconcentration potential were examined. Roughly, the behavior of the surfactants having 10–30 oxyethylene subunits can be described as the behavior of the system of two peaks: the dispersed one, which shifts toward a negative direction with the increase of concentration, and the narrow one, which has a stable position. The narrow peak is useful for analytical purposes whereas the dispersed one makes the background current worse. The surfactant having 40 oxyethylene subunits forms two narrow closely located peaks, useful for analysis. The peaks of all surfactants increase linearly with the increase of the number of oxyethylene subunits, under selected conditions.
Determination of copper in process manganese sulfate electrolyte by differential pulse anodic stripping voltammetry
Authors: Adeloju Samuel B. , Cui Chun‐Guo 
Published: May 2005

AbstractA method is described for the reliable determination of copper in manganese sulfate electrolyte by the differential pulse anodic stripping voltammetry on a glassy carbon mercury film electrode (GCMFE). Unlike on the hanging mercury drop electrode, the high manganese sulfate electrolyte (1.3 M) proved to be an adequate medium when acidified with nitric acid for the determination of copper on a GCMFE. Under these conditions, the copper response was more pronounced due to the formation or either an intermetallic compound with manganese or a manganese oxide, which oxidizes during the stripping step. In contrast, the buffering of the electrolyte to pH ˜5 with an acetate buffer was inadequate for the copper determination. The use of the acetate buffer was also proved to be responsible for the irreproducible behavior of the copper response on mercury electrodes. Based on the preliminary acidification of the manganese sulfate electrolyte with nitric acid and the use of a 2 min deposition period, a linear concentration range between 0–100 μg/1 and a minimum detectable amount of 1 μg/1 copper above the background level present in the process plant electrolyte were accomplished. The precision of the method (relative standard deviation) ranges between 1 and 2%. Recovery studies indicated that the voltammetric method is capable of detecting 96–100% of the copper present in the high manganese sulfate electrolyte medium, providing that the sample is acidified initially with nitric acid.
An electrochemical capillary fill device for the analysis of glucose incorporating glucose oxidase and ruthenium (III) hexamine as mediator
Authors: Morris N. A. , Cardosi M. F. , Birch B. J. , Turner A. P. F. 
Published: May 2005

AbstractThis article describes a coulometric measurement device for glucose based on thin‐layer bulk electrolysis. The analysis is carried out in a specially constructed cell, the electrochemical capillary fill device, which has a total volume of less than 20μl. Once the sample enters the cell by capillary action, the freeze‐dried assay components (glucose oxidase, ruthenium (III) hexamine, buffer salts, etc.) become solubilized and quickly disperse throughout the volume of the cell. After a period of one min, the time taken for the enzyme catalyzed oxidation of glucose to gluconic acid to reach completion, a potential step is applied and the current transient, resulting from the oxidation of reduced mediator at the working electrode, integrated over a period of 60 s. From the resultant charge value, the concentration of glucose in the sample can be unambiguously determined. The response of the sensor is both linear and accurate over the range 2–30 mM, which covers the normally accepted range for blood glucose levels in diabetic patients. The second order rate constant for the reaction between reduced glucose oxidase and ruthenium (III) hexamine was evaluated by conducting a numerically based analysis that was designed to separate the diffusional and catatytic components of current transients.
Benzo‐18‐crown‐6 and its lariat ether derivatives as ionophores for potassium, strontium, and lead ion‐selective electrodes
Authors: Attiyat Abdulrahman S. , Christian Gary D. , Cason C. Victor , Bartsch Richard A. 
Published: May 2005

AbstractIon‐selective microelectrodes were prepared by coating a matrix containing the crown ether benzo‐18‐crown‐6 or one of five polyether ring‐substituted benzo‐18‐crown‐6 derivatives on a preconditioned silver wire in a flow cell. Responses of the electrodes toward lithium, sodium, potassium, magnesium, calcium, strontium, and lead were measured. Selectivity coefficients were obtained by the matched potential, fixed interference, and separate solution methods. Compared with benzo‐18‐crown‐6, the nature of the side arm in the lariat ether derivatives was found to influence the selectivities in different ways. For specific ionophores, high selectivities of potassium over lithium, sodium, magnesium, calcium, and strontium, of strontium over magnesium and calcium, and of lead over magnesium, calcium, and strontium were demonstrated.
Bioaccumulation and quantitation of metals at peat moss‐modified electrodes
Authors: Wang Joseph , Naser Najih , Darnall Dennis , Gardea‐Torresdey Jorge 
Published: May 2005

AbstractPlant materials of the genus Sphagnum have long been known to absorb cations preferentially from dilute solutions. Preconcentrating modified electrodes based on the incorporation of peat moss within carbon paste matrices, have been designed for bioaccumulating copper ions prior to their voltammetric quantitation. Operational conditions, such as paste composition, solution pH or ionic strength, accumulation time, and voltammetric waveform are characterized and optimized to allow quantitation of submicromolar concentrations. The surface is regenerated by placing the electrode in a hydrochloric acid solution, allowing the use of a single electrode in multiple determinations (RSD of 6% for 15 repetitions). The plant modifiers also strongly bind and retain multiple charged counterions. These surface‐bound ionic metal complexes are able to mediate electron transfer with solution species (such as hydrogen peroxide). The approach could be extended to other plant‐material modifier/analyte systems, as well as for preconcentration for other trace techniques. Preliminary data are given for the Spanish moss/silver system.
Liquid chromatography amperometric detection of catechol, resorcinol, and hydroquinone with a copper‐based chemically modified electrode
Authors: Zhou Jianxun , Wang Erkang 
Published: May 2005

AbstractA copper‐based chemically modified electrode (CME) has been constructed and characterized for flow‐through amperometric detection of catechol, resorcinol, and hydroquinone. Novel potential dependence of the detector response was first obtained for these analytes at the Cu CME, where negative peaks together with positive ones were observed in one definite chromatogram using amperometric detection. Its advantages in chromatographic applications were demonstrated. From these observations it is proposed that the detector response was governed by formation of copper complexes with the solutes. A dynamic linear range over two orders of magnitude was obtained, when operating the detector at +0.10 V vs. SCE, from which ng detection limits were achieved.
Electrochemical investigations of 3‐(p‐sulfamoylphenylhydrazono)‐2,4‐pentanedione at pyrolytic graphite electrode
Authors: Goyal R. N. , Kumar Anoop , Bhargava Sandhya 
Published: May 2005

AbstractThe electrochemical behavior of 3‐(p‐sulfamoylphenylhydrazono)‐2, 4‐pentanedione has been studied in the pH range 2.2–10.2. It was observed that sulfamoylphenylhydrazone undergoes electrooxidation as well as electroreduction at the surface of a pyrolytic graphite electrode (PGE). The oxidation or reduction peaks observed can be used for the detection of this compound. The products corresponding to both processes have been separated and characterized using IR, NMR, and mass spectra. The reaction pathways have been proposed to account for the voltammetric, coulometric and spectral behavior.