bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation in PED response at a gold microelectrode as a function of waveform parameters when applied to alditols and carbohydrates separated by capillary electrophoresis
Authors: Roberts Robert E. , Johnson Dennis C. 
Published: May 2005

AbstractResults are presented from a systematic study of the noise (N) and peak‐to‐noise ratio (P/N) obtained for pulsed electrochemical detection (PED) at a gold micro‐wire electrode applied to a mixture of alditols and monosaccharides separated by capillary electrophoresis (CE). The electrode potentials and time periods for oxidative cleaning and reductive reactivation of the electrode were held constant in the PED waveform at minimum allowable values and the time period for digital integration of electrode current (tint) was varied from 50 to 800 ms by 50‐ms intervals. The value of N was virtually independent of tint and P/N increased approximately as a linear function of tint in the range 50–200 ms corresponding to waveform frequencies in the range 4.5–2.7 Hz. A detection limit of 9 fmol glucose was determined for a 4‐nL injection using tint = 200 ms.
An enzyme‐containing ink for screen‐printed glucose sensors
Authors: Nagata Ryohei , Yokoyama Kenji , Durliat Hélène , Comtat Maurice , Clark Susan Anne , Karube Isao 
Published: May 2005

AbstractA glucose sensor employing ferrocene‐bound glucose oxidase was fabricated by the screen printing technique. In order to obtain high GOD activity, glucose oxidase (GOD) was modified with ferrocenecarboxylic acid (fc) as an electron mediator. Simultaneous spectroscopic and electrochemical analyses showed that ferrocene‐bound GOD (fc‐GOD) displayed an increase in catalytic current. The ferrocene acts as an electron transfer relay between the active center of the enzyme and the gold electrode. The screen printing process was used to print successfully the unique fc‐GOD containing ink onto the gold electrode patterned on the glass plate. The fc‐GOD containing ink was specially developed to be suitable for the printing apparatus. The printed glucose sensor was shown to offer a stable calibration profile and stable electrochemical properties.
Metal‐dispersed screen‐printed carbon electrodes
Authors: Wang Joseph , Pedrero Maria , Pamidi Prasad V. A. , Cai Xiaohua 
Published: May 2005

AbstractNickel‐, cobalt‐, copper‐, and palladium‐dispersed carbon inks are used for screen printing of electrocatalytic sensors. The resulting strips couple the advantages of mass‐producible disposable electrodes and effective catalytic surfaces. The dispersed metal particles lead to a marked decrease in the oxidation potential for carbohydrates, amino acids, aldehydes or alcohols. Characterization of the electrocatalytic behavior and the analytical (sensing) performance are reported. Applicability to wine samples is illustrated.
Thin‐layer composite enzyme electrodes for glucose determinations
Authors: Zawodzinski Thomas A. , Campbell Carmen , Davey John , Gottesfeld Shimshon , Serach James , Wilson Mahlon , Rishpon Judith 
Published: May 2005

AbstractWe have prepared amperometric glucose sensitive electrodes with a composite active layer consisting of Nafion, glucose oxidase, and carbon‐supported platinum particles. A particularly advantageous configuration results from the use of such a film on a gas diffusion electrode. We demonstrate that the gas diffusion electrode configuration enables us to supply oxygen from the back of the electrode, thus providing the capability of operating the sensor independent of dissolved oxygen. The insensitivity to solution oxygen concentration has been demonstrated by monitoring the glucose response of the electrode after extensive deoxygenation of solution. Cast composite layers yield mechanically robust coatings with high enzyme loadings, and thus high sensitivity to glucose. The electrode responds rapidly and is stable over a long period (90% activity after more than half a year) when stored in solution. We have optimized the composition of the sensitive layer with respect to Nafion to C/Pt ratio and enzyme loading.
Reinvestigation of a ferric ion‐selective electrode based on the chalcogenide glass FexSe60Ge28Sb12(x = 1–10)
Authors: Koenig Christian E. , Graber Erich W. 
Published: May 2005

AbstractA ferric ion‐selective electrode based on the iron containing chalcogenide glass FexSe60Ge28Sb12(X = 1–10) was reinvestigated in order to optimize the electrode characteristics and to elucidate the mechanism of the potential determining process. By modifying the preparation procedure of the chalcogenide glass described in the literature and of the electrode configuration highly stable sensors were obtained. These sensors show super‐Nernstian slopes of the calibration plots of about 65 mV/decade, selectivity coefficients of about 10−4for several heavy metal ions and a potential drift of 3–4 m V/h due to some slow corrosion process occuring at the electrode surface. Furthermore the data of impedance, cyclovoltammetric, and XPS experiments show that the conditioning process of the electrode leads to a modified surface layer which behaves like a specific ion exchanger for Fe3+ ions. In contact with a Fe3+ containing electrolyte, the exchange of Fe3+ ions between the electrolyte and the modified surface layer leads to the injection of holes from the surface layer into the bulk of the chalcogenide glass. Thus the fermi level of the material is shifted, causing the observed potential change.
An indirect voltammetric approach for the determination of cyanide at a chemically modified electrode
Authors: Sousa Maria de Fátima B. , Godinho Oswaldo E. S. , Aleixo Luiz M. 
Published: May 2005

AbstractAn indirect voltammetric procedure for measuring free cyanide ions, using a chemically modified carbon‐paste mercury‐sensitive electrode, is described. The method is based on competitive HgII‐complex formation reactions between an organic ligand at the electrode surface and CN− ions in solution. A linear decrease of the peak current of mercury in a solution of a defined Hg2+ concentration was observed, when the cyanide concentration was increased from 8.0 to 49.0 mg/L (0.3‐1.9 × 10−6M). The relative standard deviation for five independent measurements was 8%.
Optimization by experimental design of the adsorptive stripping voltammetric parameters in the determination of cinoxacin
Authors: Gratteri Paola , Furlanetto Sandra , Pinzauti Sergio , Leardi Riccardo , Corti Piero 
Published: May 2005

AbstractThe quinolone antibacterial agent cinoxacin was studied by adsorptive stripping voltammetry making use of its controlled interfacial accumulation on a static mercury drop electrode. Measurements were obtained in differential pulse mode and optimized by experimental design. The chemometric approach allowed the identification of a strong interaction between pH and pulse amplitude. The dynamic linear range of calibration was extended from 0.4 to 9 × 10−8 M. Analyses of cinoxacin capsules and spiked human urine sample were carried out without the need of previous extraction or filtration. A cleanup procedure was required to separate cinoxacin from the human plasma matrix prior to adsorptive stripping analysis.
Ultrasonic extraction and field‐portable anodic stripping voltammetry of lead from environmental samples
Authors: Ashley Kevin 
Published: May 2005

AbstractUltrasonic extraction of lead from environmental samples, followed by anodic stripping voltammetric (ASV) analysis using a field‐portable ASV instrument, was evaluated. Representative lead‐containing standard reference materials were subjected to ultrasonic agitation in dilute nitric acid, and the lead subsequently determined by ASV. Recoveries of lead were found to be statistically equivalent to those obtained previously by means of hotplate concentrated acid digestion and atomic spectrometric analysis. Laboratory‐prepared air filter samples were also analyzed for lead content by using the ultrasonic extraction/portable ASV analytical protocol. For duplicate laboratory‐prepared air filter samples, results from microwave digestion and atomic absorption analysis compared well with those from ultrasonic extraction and portable ASV analysis. The lower detection limit for the ultrasound/portable ASV method was found to be less than 1 ppb Pb in solution, or < 0.1 μg Pb/filter. The results suggest that the method may allow for the on‐site determination of lead in environmental samples such as paint, dust, soil and workplace air.
Biosensors based on cross‐linking of biotinylated glucose oxidase by avidin
Authors: Vreeke Mark S. , Rocca Patrick 
Published: May 2005

AbstractAvidin, having four biotin binding units, cross‐links and immobilizes glucose oxidase (GOX) labeled with multiple biotins (B‐GOX) when solutions of B‐GOX and avidin are mixed on an electrode. The H2O2 flux generated in the B‐GOX catalyzed oxidation of glucose by dissolved O2 is measured as an electroreduction current at a horseradish peroxidase (HRP) redox conducting hydrogel electrode poised at +100 mV (Ag/AgCl). The sensitivity of the resulting glucose sensor is 0.14 A cm−2 M−1 with a linear range up to 2mM glucose.
Determination of casein by square‐wave voltammetry using electrocatalytic reduction of nickel(II)
Authors: Perez Ambrosio Sanchez , DelgadoZamarreño Maria M. , Mendez Jesús Hernandez , Turrion Nieves María B. 
Published: May 2005

AbstractThe catalytic peak produced at −0.80 V (vs Ag/AgCl) by the presence of casein in the reduction of NIII on a dropping mercury electrode in sodium acetate medium was explored using square‐wave voltammetry (SWV). The effects of the electrochemical variables on SW voltammograms were studied and optimum operating conditions were established (10−2 M NiII, 1 M sodium acetate, pH 7.0 and temperature of 23° C). Good linearity between the SW voltammetric peak current and casein concentrations in the 0–128 mg L−1 range was obtained. An electrocatalytic method is proposed for the determination of casein with rapid and precise results (relative standard deviation of 5.2 %).
Submersible bioprobe for continuous monitoring of peroxide species
Authors: Wang Joseph , Cepría Gemma , Chen Qiang 
Published: May 2005

AbstractA peroxidase‐based biosensor, coupled to a newly designed remote probe, is used for monitoring peroxide species at large sample‐instrument distances. The new bioprobe can operate over a broad pH and ionic‐strength ranges relevant to natural water conditions. Measurements of micromolar levels of hydrogen peroxide and 2‐hutanone peroxide in untreated river and groundwater samples are demonstrated, and prospects and challenges for remote field applications are discussed.
Determination of metals in a multicomponent system by differential pulse and alternating current anodic stripping voltammetry
Authors: Locatelii Clinio , Vasca Ermanno , Bighi Corrado , Fagioli Francesco , Garai Tibor 
Published: May 2005

AbstractA combination of sensitive and selective voltammetric methods, namely differential pulse (DPASV) and fundamental and second harmonic alternating current anodic stripping voltammetry (ACASV) were found to be very suitable techniques for the simultaneous determination of metal species having half‐wave potentials close to one another. The simultaneous determination of traces of CuII, BiIII, SbIII, PbII, CdII and SnII is described using 0.1 M HCl as the supporting electrolyte with the subsequent addition of 0.02 M EDTA or 1.0 M NaOH (for the analysis of CuII, SbIII and SnII, respectively). A semistationary mercury electrode (long lasting sessile drop mercury electrode) was used as the working electrode. A saturated calomel electrode (SCE) and a platinum electrode were used as the reference and auxiliary electrodes, respectively. The analytical procedure was verified with the analysis of standard reference material NBS‐SRM 631 Spectrographic Zinc Spelter LVl. Precision and accuracy, expressed as relative standard deviation and relative error, respectively, were 3 to 5%, while the detection limits were of the order of 10−8 to10−10 M in the case of element examined.
Adsorptive‐catalytic stripping voltammetry‐enhanced reduction current of adsorbed CoII tetraaza[14]annulene complex in the presence of CO2
Authors: Muszalska Elżbieta , Bilewicz Renata 
Published: May 2005

AbstractThe macrocyclic cobalt(II) complex CoL (LH2 = 5,14dihydrodibenzo[b,i][1,4,8,11] tetraaza[l4]annulene) can be adsorptively preaccumulated on mercury electrodes from highly diluted aqueous solutions. The adsorbed CoII complex undergoes one‐electron reduction with subsequent protonation of [CoL]− to CoLH, also adsorbed on mercury. The electrode covered with adsorbed complex may be used to detect CO2, since upon substitution of argon by CO2 a large catalytic peak is observed at the potentials of CoLH complex reduction. At constant CO2 concentration, the peak first increases proportionally to the extent of coverage of the electrode with the adsorbed complex and then becomes constant when monolayer coverage is attained. At a monolayer covered electrode the catalytic reduction signal increases proportionally to the increase of CO2 concentration. The usefulness of the normal pulse voltammetry version of the adsorptive‐catalytic stripping procedure is also shown.
The reduction of m‐iodo‐nitrobenzene: A comparative study using microdisk and channel electrodes
Authors: Compton Richard G. , Dryfe Robert A. W. , Eklund John C. , Nei Lembit , Page Stephen D. 
Published: May 2005

AbstractThe reduction of m‐iodo‐nitrobenzene, m‐I‐ϕ‐NO2, in acetonitrile solution was studied using both microdisk and channel electrodes. A voltammetric wave with a halfwave potential of −1.09 V (vs. saturated calomel reference electrode) was observed and both techniques showed that more than one electron was passed per molecule of the substrate. The rates of mass transport were varied in both electrode systems by changing either the electrode radius in the case of microelectrodes, or the electrolyte flow rate in the case of channel electrodes so as to identify the kinetics and mechanism of the electrode process. Both approaches indicated an ECE mechanism operates: magnified image where HS denotes the solvent‐supporting electrolyte system. The rate constants for the decomposition of the radical anion, [m‐I‐ϕ‐NO2]˙, as determined by the two methods, were in excellent agreement and equal to 0.30(0.05) s−1. Comparisons between the use of microdisks and channel electrodes for such studies are reported and their relative sensitivity assessed.
Detection of cytochrome c using a conducting polymer mediator containing electrode
Authors: Lu Wen , Zhao Huijun , Wallace Gordon G. 
Published: May 2005

AbstractIn this work, we have demonstrated the feasibility of cytochrome c detection using a novel mediator‐incorporated conducting polypyrrole‐based electrode. The mediator used was Fe(CN). The effect of buffer solution pH and electrochemical conditions on the voltammetric responses of cytochrome c have been investigated. The analytical utility of this electrode has been demonstrated using flow injection analysis.
A potentiometric polypyrrole‐based glucose biosensor
Authors: Trojanowicz Marek , Hitchman Michael L. 
Published: May 2005

AbstractA new concept is described for monitoring a biomolecule with a sensor having an enzyme entrapped in a conducting polymer. This is based on the sensitivity of the electroactive polymer itself to changes of pH in solution. The concept has been investigated for a glucose sensor with glucose oxidase (GOD) immobilized in a polypyrrole (PPy) layer on an inert platinum electrode. Measurements with a Pt/PPy/GOD electrode for glucose concentrations in the physiological range gave a linear correlation with logarithm of concentration over one decade with a satisfactory dynamic response. There was practically no change of slope or range of linear response to glucose after several days of use; this was in contrast to the amperometric response of the detector when there was about a 50% loss of sensitivity.
On the mechanism of electrooxidation of hydrazine on platinum electrodes in acidic solutions
Authors: García Maria D. , Marcos Maria L. , Velasco Jaime González 
Published: May 2005

AbstractA systematic study of the electrooxidation mechanism of hydrazine on Pt electrodes in 0.5 M H2SO4 solutions has been made. The experimental rate equation found is magnified image This can be theoretically explained by a five step mechanism. The log I vs. log Chyd linear plot that results in the determination of the reaction order respect to hydrazine concentration can be used as a working curve for quantitative analytical determination of hydrazine concentrations. A mechanistic explanation has been found for the unusual dependence of the Tafel slope with the pH value.
Effect of membrane composition on the flow‐injection response of an ion‐selective electrode: A comparative study based on selectivity coefficients calculated using a data linearization technique
Authors: Davey David E. , Mulcahy Dennis E. , O'connell Gregory R. 
Published: May 2005

AbstractCommercial iodide, sulfide and cadmium‐selective electrodes and four electrodes based on laboratory‐prepared pressed membranes, the latter composed of either silver iodide or a mixture of silver iodide and sulfide, were assessed for their flow‐injection response towards iodide in the absence and presence of bromide, thiocyanate and thiosulfate. With the exception of a pressed membrane based on a 3:1 mixture of AgI and Ag2S, which gave rise to erratic, irreproducible potentials, all the electrodes responded rapidly to iodide. While detection limits were generally similar, slope factors ranged from −44.6 mV/decade for a pressed AgI membrane to −61.2 mV/decade for a 1:3 AgI/Ag2S membrane. Selectivity coefficients were determined for each of the electrodes by intercalating mixed iodide‐interferent solutions into a 10−6 M iodide carrier stream, then processing the resultant data by both the accepted IUPAC graphical method and a proposed data linearization technique. Although the two methods returned comparable results for the electrodes and interferents examined, the linearization procedure would be the preferred option in cases where the selectivity coefficients determined are greater than unity. Using electrode membranes composed of either AgI or AgI/Ag2S, a trend in selectivity was observed which suggests a mechanism of response towards the interferents involving the oxidation of the sulfide in the membrane to either sulfate or elemental sulfur.
Electrochemical oxidation of the diuretic indapamide
Authors: Legorburu María J. , Alonso Rosa M. , Jiménez Rosa M. 
Published: May 2005

AbstractThe electrochemical oxidation of the 3‐(Aminosulfonyl)‐4‐chloro‐N‐(2,3‐dihydro‐2‐methyl‐1H‐indol‐1‐y1)benzamide, Indapamide, was studied in aqueous alcoholic media (9:91 MeOH+H2O, pH range 1–13) and two different ionic media (KNO3 and KCl) at carbon electrodes. The oxidation processes attributed to indoline ring and benzamide moiety have been shown to be irreversible and diffusion‐controlled over the entire pH range in both media. A differential‐pulse voltammetric method was developed upon the basis of the voltammetric peak due to indoline ring, at pH around 2.3 (phosphate buffer) and using KNO3 as ionic medium. The peak current ip, showed a linear relationship with concentration in the range 5.92 × 10 −7 M–1.86 × 10 −5 M with a detection limit of 9.87 × 10−8 M (37 ppb) and a reproducibility (in terms of relative standard deviation) of 4.8% and 9.3% for 10 determinations of 2.67 × 10−6 M and 1.07 × 10−6M concentrations, respectively. The differential‐pulse voltammetric method for Indapamide was applied to assays of pharmaceuticals (Tertensif, 2.5mg) and urine samples.
Evaluation of diffusion coefficients of metallic ions in aqueous solutions
Authors: Kariuki Stephen , Dewald Howard D. 
Published: May 2005

AbstractMany techniques are available for the determination of diffusion coefficients of ions in aqueous solutions. A review of classical and modern techniques is presented. Non‐electrochemical methods are discussed briefly. Electrochemical methods reviewed include chronoamperometry, chronopotentiometry, polarography, and hydrodnamics. Selected values of the diffusion coefficients determined by these electrochemical methods of the metallic ions AgI, BiIII, CdII, CuII InIII, PbII, TlI, and ZnII are presented.
Cyclic voltammetry with harmonic lock‐in detection: Applications to flow streams
Authors: Cullison John K. , Kuhr Werner G. 
Published: May 2005

AbstractThe second harmonic frequency is monitored using a conventional lock‐in amplifier in a continuous scan cyclic voltammetric experiment. The background charging current is predominantly composed of odd harmonic frequencies, while the analyte Faradaic signal is composed of both odd and even harmonic frequencies. By ‘locking‐in’ on the second harmonic frequency one can isolate the Faradaic current from the charging current in the frequency domain. Model compounds (hexaammineruthenium(III) chloride, ferrocene) at carbon and gold microelectrodes as well as carbohydrates at copper microelectrodes were examined in flow injection analysis experiments. Limits of detection an order of magnitude lower than DC amperometry were observed.
Ion‐selective electrodes – analogies and conclusions
Authors: Pungor Ernǒ 
Published: May 2005

AbstractThe author investigated the working mechanism of ion‐selective electrodes. The contradictions of theories deduced from so‐called analogous phenomena were discussed in detail. Based on experiments made by his research group he came to the conclusion that only the surface (the active groups located there) takes part in the potential‐determining reaction, and the bulk resistance of the membrane has a role only in the selection of the instrument used for potential measurement.
Cathodic stripping voltammetric determination of metallothioneins
Authors: Scarano Gioacchino , Morelli Elisabetta 
Published: May 2005

AbstractA cathodic stripping voltammetric method for the determination of metallothioneins (MT) is proposed. The procedure is based on the controlled adsorption of the protein on the mercury electrode after addition of an excess of CuII to the solution. The effects of accumulation time, adsorption potential and copper concentration have been examined and the analytical procedure has been optimized. Using an accumulation time of 300 s, a MT concentration of 0.2 nM can be detected.
Detection of glucose at a rotating gold composite electrode by pulsed amperometric detection
Authors: Elliott Peter T. , Olsen Scott A. , Tallman Dennis E. 
Published: May 2005

AbstractSegregated composite electrodes mimic microelectrode ensembles. In this preliminary report, the use of a rotating gold‐polychlorotri‐ fluoroethylene (or Kel‐F, a 3M Company polymer) composite electrode in combination with pulsed amperometric detection (PAD) is described for the detection of glucose. Comparisons are made with results obtained at a solid gold disk electrode. The composite electrode exhibits a higher signal and a lower background than does the solid gold electrode. In terms of current density, the enhancement of the signal above the background is over 3‐fold, similar to that observed with segregated graphite composite electrodes used in a constant potential mode. Little or no glucose signal is observed at either the solid gold or the gold composite electrode when employed in the constant potential mode. In the PAD mode, the signal is stable for periods in excess of an hour.