bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of nickel and cobalt in wastewaters and seawater by constant current stripping potentiometry with nitrite enhancement of the stripping signal
Authors: Nan Chen Guo , Cardwell Terence J. , Vincente‐Beckett Victoria A. , Hamilton Ian C. , Scollary Geoffrey R. 
Published: May 2005

AbstractA rapid and highly sensitive method using constant current stripping potentiometry for the determination of nickel and cobalt in seawaters and industrial wastewaters has been established. The method is based on the adsorptive accumulation of nickel and cobalt in the presence of either dimethylglyoxime (DMG) or α‐benzyldioxime (α‐BD) prior to stripping using a constant reducing current. Nitrite is used in the stripping step for the catalytic enhancement of the stripping signal. Analytical protocols for standard solutions using DMG or α‐BD show good precision (RSD's between 3 and 4% on the same film) and detection limits (30 ng/L for Ni/DMG; 10‐ng/L for Co/DMG; 9ng/L for Co/α‐BD). However, iron interferes significantly with the determination of cobalt using α‐BD. With DMG, the simultaneous determination of nickel and cobalt is possible and has been developed into a protocol readily applicable to the routine determination of these metals. The analytical protocol is rapid, easy to perform and the results are in agreement with those obtained by graphite furnace atomic absorption spectrophotometry. The DMG procedure has also been optimized for the determination of cobalt alone, which has advantages for determinations at concentrations of 1 μg/L or less.
Redox kinetics in cathodic stripping square‐wave voltammetry
Authors: Lovrić Milivoj , Mlakar Marina 
Published: May 2005

AbstractSeveral redox systems with reactants which are immobilized at the electrode surface (EuSal complex, SeIV and SeIV in the presence of CuII, cysteine and p‐nitrophenol) were studied by square‐wave voltammetry to examine whether their redox kinetics can be measured by using the phenomenon of the ‘quasireversible maximum’. This is explained in detail. The following standard rate constants are obtained: EuSal complex ks = 720 ± 31 s−1, SeIV/CuII, log [ks/(cms−1)] = 0.94 ± 0.9, cysteine, log [ks/(cms−1)] = 0.6 ± 0.9 and p‐nitrophenol, ks > 1200 ± 50 s−1.
Determination of mercury and silver at a modified carbon paste electrode containing glyoxal bis(2‐hydroxyanil)
Authors: Won Mi‐Sook , Moon Deog‐Whan , Shim Yoon‐Bo 
Published: May 2005

AbstractModified carbon paste electrodes(CPEs) for the analysis of mercury and silver have been constructed by incorporating a Schiff base, glyoxal bis(2‐hydroxyanil) (GHA) into the graphite powder and mixing with Nujol oil. Simple immersing of the GHA‐modified CPE into the measuring solution led to the chemical deposition of the metal ions onto the electrode. The cyclic, differential pulse, and stripping voltammetry were used to characterize the modified electrodes, which selectively responded to the mercury(II) and silver(I) ions. The analyses of Hg and Ag were carried out separately with the CPE in the acetate buffer and neutral aqueous solution. The electrode surface was regenerated after each measurement, by cycling the potential from more positive than that for the stripping of the reduced Hg to the more negative than that for the reduction of AgI ion. After seven deposition/measurement/regeneration cycles, the peak current of the analyte decreased. The response reproduced around 5% relative standard deviation using the differential pulse stripping voltammetry. The detection limits for HgII and AgI ions were 1.0 × 10−9 M and 1.0 × 10−10 M, respectively, for 40 min of deposition. After pretreatment of silver(I) ion with KCl, we could not observe any interference by other metal ions in the determination of the HgII ion in aqueous solution. Our results obtained in the determination of mercury are verified using a certified standard urine reference material, SRM's 2670 (trace elements in urine).
Electrooxidation of ascorbic acid on the dispersed platinum glassy carbon electrode and its amperometric determination in flow injection analysis
Authors: Casella Innocenzo G. 
Published: May 2005

AbstractCyclic voltammetry was used to investigate the electrochemical behavior of ascorbic acid at a platinum modified glassy carbon electrode (Pt‐CME) in perchloric acid solutions. Tafel slopes, reaction orders and pH effects were evaluated and a possible electrooxidation mechanism is reported.Experiments in flow injection analysis were performed to characterize the electrode as an amperometric sensor for the determination of ascorbic acid. The effects of several common interferences on the amperometric signal were estimated.The electrode stability, precision, limit of detection and linear range were evaluated at low and high potentials (i.e., 0.55V and 1.0 V). In particular, at 0.55V the limit of detection was 25 ng mL−1 and the calibration graph was linear in the range 60 ng mL−1350 μg mL−1 (correlation coefficient 0.999). The mechanism of the oxidation of ascorbic acid on the Pt‐CME is rather similar to the bulk platinum electrode, but in FIA a different behavior was observed. In particular, the Pt‐CME, after repetitive injections of ascorbic acid, shows very reproducible amperometric signals without recourse to pulsed waveform potentials. In contrast, bulk platinum electrodes shows a significant poisoning effect towards the electrooxidation of ascorbic acid, thus pulsed amperometric techniques are necessary to preserve the catalytic performance. Moreover, the Pt‐CME in comparison with the bulk platinum electrode, shows significant oxidation currents in the wide range of potentials (i.e., 0.4V–1.5 v).Examples of the determination of ascorbic acid in fruit juice were achieved by flow injection analysis. Good levels of recovery (99–103%) were obtained. For comparison, the ascorbic acid was also determined in these samples by using a chromatographic method with UV detection at 254 nm.
Cadmium and lead complexation by anodic stripping voltammetry with a mercury microelectrode
Authors: Correia dos santos Margarida M. , Goņalves Maria L. Simões , Capelo Sofia 
Published: May 2005

AbstractComplexation reactions of lead by glutamic acid in KNO3 0.1 M and cadmium by glycine at two ionic strengths (0.1 MKNO3 and 2 × 10−3 M borate buffer) have been used to : 1) compare the stripping response in DCASV (direct current anodic stripping voltammetry) and DPASV (differential pulse anodic stripping voltammetry) at large (hanging mercury drop electrode: HMDE) and small (thin film mercury microelectrode deposited on Pt/lr: μME) electrodes, 2) test classical DeFord‐Hume's method with microelectrodes coupled to DCASV and DPASV, and 3) analyze the suitability of both electrodes HMDE and μME coupled to anodic stripping voltammetry to measurements in freshwaters. Indeed due to the mass transport characteristics at microelectrodes, the fraction of a metal which contributes to the current may well be different from that at a conventional size electrode. The obtained results are in all the situations consistent among themselves and in good agreement with literature.
The voltammetric behavior of the plasmin‐modified carbon paste electrode in the presence of an electrogenic substrate
Authors: Longchamp Sylvie , Randriamahazaka Hyacinthe N. , Nigretto Jean‐Maxime 
Published: May 2005

AbstractThe catalytic properties of plasmin (Pln), irreversibly adsorbed on carbon paste electrodes are considered. The assay of the immobilized enzyme could be achieved with the availability of a specific and electrogenic substrate contained in the solution. The synthesis of this substrate, designated as S2644, was specially initiated for this purpose. The electrochemical properties of the electrode surface upon exposure to solutions containing the substrate or the products involved in the catalysis, or both, were examined by performing cyclic voltammetric measurements directly at the modified electrode. Results showed the dependence of the electrode potential conditions on the surface catalytic activities and the effect of the adsorbed species in the heterogeneous catalysis.
Electrochemical deposition of prussian blue films across interdigital array electrodes and their use in gas sensing
Authors: McCormac Timothy , Cassidy John , Cameron David 
Published: May 2005

AbstractPrussian Blue films were deposited across carbon ink array electrodes and solid‐state voltammetry was performed. The current measured from the array, when the potential across the two electrode array was +0.5 V, was found to be dependent upon the nature of the bathing gas. It was seen that methanol, water vapor and dichloroethane lead to an increase in the measured current. Upon switching between nitrogen and the aforementioned gases the responses obtained were reversible and rapid, with a response time in the order of 5s. It is concluded that the bathing gas does not act as an oxidant or reductant but it helps to solvate the internal counterionic species, and leads to an increase in mobility.
Enzyme electrode for the determination of bilirubin
Authors: Fortuney Alain , Guilbault George G. 
Published: May 2005

AbstractBilirubin oxidase (EC 1.3.3.5) catalyzes the oxidation of bilirubin to biliverdin with the concurrent reduction of oxygen to hydrogen peroxide. A platinum electrode was prepared with an immobilized bilirubin oxidase membrane. Bilirubin was determined by monitoring the increase in hydrogen peroxide concentration from the enzyme reaction. The calibration plot for bilirubin shows linearity up to 300μM. The detection limit is 0.7μM.
Electrocatalysis and measurements of hydrazine compounds at glassy carbon electrodes coated with electropolymerized 3,4‐dihydroxybenzaldehyde films
Authors: Pamidi Prasad V. A. , Wang Joseph 
Published: May 2005

AbstractChemically modified electrodes exhibiting electrocatalytic response towards hydrazine compounds were prepared by electroxidation of 3,4‐dihydroxybenzaldehyde (3,4‐DHB) on glassy carbon electrodes. The surface‐confined quinone moiety accelerates the slow oxidation of hydrazine or its methylated analogs, and allows their convenient quantitation at very low potentials. Cyclic voltammetry offers useful insights into the catalytic behavior. The electrocatalytic response is evaluated with regard to pH, scan rate, applied potential, hydrazine concentration, flow rate and other variables. When used as flow‐injection detector, the 3,4‐DHB modified electrode yields an extremely low detection limit of 5 × 10 −8M (32 pg) hydrazine. Applicability to thick‐film sensor strips is also illustrated.
Voltammetric study of the immobilization of palladium at the surface of carbon paste electrodes
Authors: Lubert Karl‐Heinz , Guttmann Markus , Beyer Lothar 
Published: May 2005

AbstractThe immobilization of palladium at the surface of unmodified carbon paste electrodes is studied by cyclic voltammetry. Some features of the voltammetric behavior of palladium(II) at carbon paste electrode in chloride solution are elucidated. Through pretreatment at 0 V (vs. Ag/AgCl) palladium is bound at the surface of the carbon paste. The amount immobilized depends on the composition of the solution, polarization time, electrode potential and stirring. During an anodic scan the surface‐bound palladium is oxidized at about +0.6 V; the well‐shaped peaks can be utilized for the determination of the immobilized Pd. The detection limit is about 5 × 10−6 M Pd2+ after 5 min polarization at 0 V (vs. Ag/AgCl) with stirring (base electrolyte 1 M KCl, pH 5.5). The rather complicated influence of hydrogen ions on the reactions at the palladium/carbon surface is discussed. Palladium and hydrogen can be “deposited” simultaneously at the carbon paste surface through cathodic polarization. Electrode reactions related to the observed peaks are suggested.
Bienzyme sensors based on poly(anilinomethylferrocene)‐modified electrodes
Authors: Mulchandani Ashok , Wang Chia‐Lin 
Published: May 2005

AbstractAmperometric bienzyme electrodes for glucose, lactic acid and glutamic acid were constructed using glucose oxidase, lactate oxidase and glutamate oxidase immobilized on a horseradish peroxidase‐poly(anilinomethylferrocene)‐modified glassy carbon electrode. In these bienzyme sensors hydrogen peroxide formed by the enzymatic reaction of glucose, lactic acid and glutamic acid with oxygen in presence of the appropriate enzyme was detected at −50 mV (vs. Ag/AgCl), by the horseradish peroxidase‐poly(anilinomethy1ferrocene)‐modified glassy carbon electrode. Because of the detection at a low applied potential, electroactive compounds such as ascorbic acid, uric acid and acetaminophen, did not interfere in analyses. The results of characterization studies of these bienzyme electrodes in terms of their, sensitivity, selectivity, linear detection range, precision, accuracy, operational lifetime stability, and long term storage stability are presented.
Iridium‐dispersed carbon paste enzyme electrodes
Authors: Wang Joseph , Rivas Gustavo , Chicharro Manuel 
Published: May 2005

AbstractAn highly selective first‐generation glucose biosensor, based on an iridium‐dispersed carbon‐paste transducer, is described. The iridium‐on‐carbon particles provide excellent electrocatalysis for both the reduction and oxidation of hydrogen peroxide. Such unique catalytic action offers convenient biosensing of glucose at very low operating potentials, where interfering reactions are negligible. Factors influencing the electrocatalytic and biocatalytic actions are elucidated, along with the analytical performance. Implications to other oxidase‐based amperometric electrodes are discussed.
Electrochemical study of the binding properties of a metallothionein I related peptide with cadmium or/and zinc
Authors: Mendieta Jesús , Rodríguez Adela Rosa 
Published: May 2005

AbstractAn electrochemical study, using differential pulse polarography, of the binding properties of the peptide Lys‐Cys‐Thr‐Cys‐Cys‐Ala Thionein Fragment [56–61] MT I (FT) with cadmium and zinc was performed. This molecule, intrinsic to the metallothionein structure, was chosen as a model of the Cd, Zn Metallothioneins ion exchange and binding properties. The influence of the addition of metal ions, cadmium and/or zinc was studied with different ratios of complexing ligand/metallic cations, FT/M(II). It is assumed that the main complex M(II)‐FT possesses a stoichiometry of 1:1, but probably two or more complexes co‐exist depending on the FT/M ratios. The equilibrium M + FT ⇌ MFT concerning the complexation equilibrium of formation and dissociation was investigated as a function of pH, going from acid to basic solution and vice versa in different mixtures: Cd:FT, Zn:FT and Cd:Zn:FT. The apparent stability constants of the complexes Cd‐FT, Zn‐FT were estimated at different pH values.
The influence of the carbon paste composition on the performance of an amperometric bienzyme sensor for L‐lactate
Authors: Spohn Uwe , Narasaiah Dontha , Gorton Lo 
Published: May 2005

AbstractThe influence of different additives on the performance of a bienzyme carbon paste electrode for the detection of L‐lactate was investigated. The influence of the pH during the adsorptive coimmobilization of lactate oxidase and horseradish peroxidase on heat pretreated carbon particles was determined in the presence and in the absence of polyethylenimine (PEI). In the absence of PEI the highest H2O2 and lactate sensitivities can be achieved after using a pHi of around 7. In the presence of PEI the response to background ratio can be increased considerably by using pHi values higher than 8.5. The lactate sensitivity is relatively independent of the pHi.The influence of the additives poly‐L‐lysine, poly‐L‐arginine, spermine, and spermidine was also investigated. The use of positively charged poly‐aminoacids improves both the sensitivity/background ratio and the long‐term stability of L‐lactate and H2O2 detection.Also the choice of both the carboneous powder and the pasting liquid has a considerable influence on the sensor characteristics. A heat treatment of the carboneous powder at 700° C for 15s improves the sensitivity of HRP modified CPEs in most cases. The replacement of the organic pasting liquid by organic solids, e.g., octadecane, heneicosane, and naphthene opens up a way to prepare robust and sensitive lactate sensors.The considered influences of the carbon paste composition and the immobilization conditions were discussed both with respect to the H2O2 and the L‐lactate responses.
Stripping analysis combined on‐line with inductively coupled plasma‐atomic emission spectrometry and with inductively coupled plasma‐mass spectrometry
Authors: Zhou Feimeng 
Published: May 2005

AbstractThis review article describes the basic principles of combining stripping analysis (SA) on‐line with inductively coupled plasma‐atomic emission spectrometry (ICP‐AES) and with inductively coupled plasma‐mass spectrometry (ICP‐MS). Four applications are reviewed to demonstrate the utility and versatility of the combination of SA with ICP‐AES or ICP‐MS: (1) preconcentration of an analyte for enhanced sensitivity, (2) elimination of detrimental ICP‐AES or ICP‐MS matrix effects, (3) elemental speciation at trace levels, and (4) sensitive multielement determination. Factors influencing the analytical performance of the on‐line coupling of SA with ICP‐AES or with ICP‐MS are also discussed.
Voltammetric multichannel measurements using silicon fabricated microelectrode arrays
Authors: Paeschke Manfred , Dietrich Frank , Uhlig Albrecht , Hintsche Rainer 
Published: May 2005

AbstractA modular voltammetric multichannel detection system has been developed for use in flow analysis. Two different types of multichannel potentiostats, an adjustable and a ground‐fixed potentiostat, are realized. Both types work with up to sixteen independent working electrodes at one chip electrode array and are controlled through a personal computer and a microcontroller. Simultaneous difference pulse and cyclic voltammetric procedures are realized. Platinum thin‐film array electrodes have been arranged on silicon wafers as pairs of interdigitated microband electrodes (interdigitated array electrodes; IDA) with an interelectrode gap in the submicrometer range. Furthermore the multichannel electrodes in a flow system were used to characterize the highly sensitive flow profiles and flow rate measurements using redox mediators. A brief description of applying the multichannel device for ‘window’ stripping of heavy metals is given.
Flow injection monitoring and analysis of mixtures of simazine, atrazine, and propazine using filter‐supported bilayer lipid membranes (BLMs)
Authors: Nikolelis Dimitrios P. , Siontorou Christina C. 
Published: May 2005

AbstractThis work describes a technique for the rapid and sensitive electrochemical flow injection monitoring and analysis of mixtures of the triazine herbicides simazine, atrazine and propazine using stabilized systems of filter‐supported bilayer lipid membranes (BLMs) composed of egg phosphatidylcholine (egg PC) and dipalmitoylphosphatidic acid (DPPA). Injections of herbicides were made into flowing streams of a carrier electrolyte solution and a transient current signal with a duration of seconds reproducibly appeared in less than two min after exposure of the lipid membranes to the herbicides. The magnitude of this signal was linearly related to the herbicide concentration, which could be determined at sub‐micromolar level. The mechanism of signal generation was related to a rapid adsorption of the triazine followed by a slow aggregative process of the herbicide at the surface of BLMs with a consequent rapid reorganization of the membrane electrostatics. Repetitive cycles of injection of herbicides have shown no signal degradation during each cycle. The time of appearance of the transient response was different for each triazine and increased to the order of simazine, atrazine and propazine which has allowed selective detection and analysis of these triazines in mixtures.
Zeolite‐modified electrodes: Analytical applications and prospects
Authors: Walcarius Alain 
Published: May 2005

AbstractA review is presented dealing with the use of zeolite‐modified electrodes (ZMEs) for electroanalytical purposes (183 references). It includes an introduction to the zeolite molecular sieves, a short overview of zeolites and electroactive species used at electrochemical interfaces modified by the presence of zeolite particles, three aspects of the electroanalysis using ZMEs, including voltammetry, potentiometry and electrocatalysis. New prospects concerning the electrochemistry of ZMEs are also discussed.
Influence of the multilayer adsorption of n‐octanol and n‐decanol on electrooxidation of the radical anion of 3‐nitrophthalic acid
Authors: Matyjasiak Anna , Stroka Jadwiga , Galus Zbigniew 
Published: May 2005

AbstractThe electrooxidation of in situ produced electrolytically radical anion of 3‐nitrophthalic acid in various water—ethanol solutions containing 0.5 M NaCIO4, 0.05 M NaOH and inhibitor has been studied. The inhibition of the electrode kinetics in the presence of n‐octanol and n‐decanol, used as inhibitors, at relative concentrations not exceeding c/cs ≤ 0.5 could be interpreted in terms of the competitive monolayer adsorption of reactant, inhibitor and solvent on the electrode surface. At c/cs > 0.8, on the capacitance‐potential curves, a subtle minima caused by formation of two layers adsorbed on the mercury electrode were observed. The kinetics of the electrooxidation of the 3‐nitrophthalic acid anion radical was additionaly influenced by this multilayer. An equation which describes the inhibition of the electrode process by two adsorbed layers of inhibitor is presented and used in the estimation of the surface coverage in the second layer.
Chemically modified microelectrodes designed for the electrochemical determination of nitric oxide in biological systems
Authors: Bedioui Fethi , Trevin Stéphane , Devynck Jacques 
Published: May 2005

AbstractSince the identification of nitric oxide (NO) as an endothelial‐derived relaxing factor, several research groups are now working to develop an understanding of the mechanism by which this free‐radical gas is synthesized, diffused and reacted from and within various cells and different biological tissues. Thus, it appears that measuring NO in biological models is very difficult because of its low concentration and fleeting existence. Indeed, NO directly reacts extremely fast with superoxide and other very active free radicals of biological importance. Most of the techniques for assaying NO release use indirect methods for estimating endogeneous NO, relying on measurements of secondary species. In fact, NO in biological systems may be directly assayed by three nonelectrochemical strategies (EPR, spectrophotometry and chemiluminescence) but these strategies suffer from being ex situ detection techniques with poor selectivity or sensitivity. The desire to measure a small amount of NO release in situ has led to an active area of research involving the design of microsensors and new amperometric microelectrode probes are now developed to detect NO. The use of electrochemistry as a potential way to do so is very promising and the reality is that surface electrode modification is needed to make the electrode material selective for NO. Therefore, the design of modified electrode surfaces using organized layers combined with microelectrodes is attractive as possible selective microsensors for the electrochemical detection of NO. A number of new amperometric approaches have reached this goal. This article consists of a critical review of electrochemical methods for the detection and determination of nitric oxide in biological materials to clarify some aspects of the reported microsensors.