bluuebunny/crossref_metadata_2025_split huggingface dataset:
An object oriented approach to electroanalytical technique implementation
Authors: Bessant Conrad , Saini Selwayan 
Published: May 2005

AbstractThis work describes the application of object oriented software design to the development of a low cost, functionally versatile, PC‐controlled potentiostat system. The implementation time for the electroanalytical techniques has been drastically reduced within the object oriented environment and it is shown how this approach simplifies the addition of new techniques without recourse to extensive software or hardware redesign. The pertinent aspects to the object oriented technique in the design of the potentiostat software are described in detail and experimental results are presented for chronoamperometry, cyclic voltammetry and square wave voltammetry for the one‐electron transfer compound, potassium hexacyanoferrate(II) in aqueous solution. It is also shown how new electroanalytical techniques based on novel potential‐time waveforms can be rapidly and easily incorporated, and experimental results for the highly sensitive pulsed amperometric detection of glucose in a stirred cell are presented.
Catalytic cathodic stripping voltammetry of 6‐mercaptopurine‐9‐D‐riboside in the presence of nickel ion
Authors: Ion Ana , Bǎnicǎ Florinel Gabriel , Luca Constantin 
Published: May 2005

AbstractDifferential pulse CSV of 6‐mercaptopurine‐9‐D‐riboside (6‐MPR) on a HMDE was investigated at pH about 7 in the presence of nickel ion. According to the value of the accumulation potential. 6‐MPR was preconcentrated either as a mercury compound or an adsorbed nickel complex. During the subsequent cathodic scan, 6‐MPR does catalyze the reduction of nickel ion giving a peak at about −0.8 V (vs. SCE). This peak enables the determination of 6‐MPR at concentrations down to 1 nM with no substantial interference from the heavy metal ions, chloride, alkali metals, complexing agents and only moderate interference by thiols and surface‐active compounds. The best sensitivity and reproducibility were achieved under the following conditions: pH 7.5 (phosphate‐acetate buffer); Ni2+, 1 mM; Eacc = −0.3 V; tacc = 1 to 2 min; scan speed = 20mV/min; pulse interval = 0.2 s.
Adsorption isotherms for atrazine on soils measured by differential pulse polarography
Authors: Vaz Carlos M. P. , Crestana Silvio , Machado Sergio A. Spinola , Mazo Luis Henrique , Avaca Luis Alberto 
Published: May 2005

AbstractDifferential pulse polarography was used to study the adsorption of atrazine on three tropical soils with different compositions regarding organic matter, clay, silt and sand. The corresponding Freundlich isotherms were determined and the calculated adsorption coefficients, KF, were 4.4, 9.9 and 5.2 mL g−1 for Pindorama, Monte Alegre and Ribeirão Preto soils, respectively. These values are in good agreement with previous reports. A comparison between the results obtained by differential pulse polarography and by gas chromatography was also performed showing that both techniques yield very similar isotherms.
Chronopotentiometric stripping of DNA at mercury electrodes
Authors: Paleček Emil , Tomschik Miroslav , Staňková Veronika , Havran Luděk 
Published: May 2005

AbstractDenatured (single‐stranded, ss) and native (double‐stranded, ds) DNAs were studied by constant current chronopotentiometric stripping analysis (CPSA) at a hanging mercury drop electrode (HMDE). In agreement with the previous voltammetric studies at neutral pH values ssDNA produced CPS cathodic peak CA (due to reduction of cytosine and adenine) and anodic peak G (due to oxidation of the guanine reduction product) at dt/dE against E curves. The same peaks produced by dsDNA were substantially smaller. Differences in heights (areas) of peaks G and CA produced by ss and dsDNAs at partial and full electrode coverage are compared and discussed. Using CPSA a well‐developed and symmetrical peak CA was obtained at low DNA concentrations compared to a poorly measurable inflection produced by differential pulse or linear sweep voltammetries under the same conditions. The CPS peak CA can be used also in adsorptive transfer stripping (AdTS, medium exchange) experiments. In the previous AdTS voltammetric measurements only peak G was exploited while the voltammetric peak CA was poorly defined to be of any use in combination with DNA‐modified electrodes. CPS peaks were measured in the presence and in absence of air. It was shown that in the presence of air peak CA is enhanced while peak G decreased. We compared the CPSA of ssDNA at the mercury and carbon paste electrodes (CPE). The CPS peak G (obtained with HMDE) seems to be the best choice for the electrochemical determination of DNA in highly diluted solution. With 10 min adsorptive preconcentration a detection limit below 20 ng of ssDNA per mL was obtained at HMDE. At CPE the limit of detection (of the same ssDNA) was at least two‐fold higher.
Poly(4‐vinylpyridine)‐coated chemically modified electrode for the detection of uric acid in the presence of a high concentration of ascorbic acid
Authors: Zen Jyh‐Myng , Chen Yao‐Jung , Hsu Chi‐Teng , Ting Yuan‐Shih 
Published: May 2005

AbstractA poly(4‐vinylpyridine)‐coated carbon paste electrode (PVP/CPE) was developed for the selective determination of uric acid (UA) in the presence of ascorbic acid (AA) by square wave voltammetry. The oxidation of UA at carbon‐based electrodes in acidic solutions suffers from interference from AA which can be oxidized at a potential close to that of UA. Due to the very distinct ability of AA and UA to form hydrogen bonds with PVP, the overlapped oxidation potentials of AA and UA can be separated. Linear calibration plots are obtained over the 0–9 μM and 10–30 μM in pH 1.1 buffer solution with slopes (μA/μM) and correlation coefficients of 3.6, 0.9992 and 7.5, 0.9989, respectively. The detection limit (3σ) is 0.2 μM. The acceptable tolerance of concentration of AA for the determination of 20 μM UA is at least as high as 0.1 mM. The practical analytical utility is illustrated by selective measurements of UA in human urine without any preliminary treatment.
Development of NOx gas sensors based on nitrate‐selective polypyrrole electrodes
Authors: Hernández Emily C. , Mortensen Charles , Bachas Leonidas G. 
Published: May 2005

AbstractA nitrate‐selective polypyrrole‐based electrode was used in the development of NOx sensor. The nitrate‐selective film was prepared by electropolymerizing pyrrole in presence of a nitrate salt. This resulted in a film that responded to nitrate in buffered media with near‐Nernstian slopes and excellent reproducibility. This electrode was incorporated into a gas‐sensing arrangement where it was immersed in a buffered compartment and separated from an acidified sample solution by a gas‐permeable membrane. Additions of nitrite to the acidified solution resulted in the production of NOx, which can cross the gas‐pemeable membrane into the buffered internal filling solution where it is trapped as nitrate and sensed by the nitrate‐selective polypyrrole electrode. This sensor arrangement resulted in detection limits in the μM range and had excellent selectivity characteristics.
Amperometric sensing of ammonia in aqueous solutions using a polyaniline‐modified electrode in flow injection systems
Authors: Trojanowicz Marek , vel Krawczyk Tadeusz Krawczyński , Zmorzyńska Małgorzata , Campanella Luigi 
Published: May 2005

AbstractPlatinum electrode modified with polyaniline by electropolymerization exhibits amperometric sensitivity to nonprotonated ammonia in aqueous solutions in the anodic range of potentials. Sensitivity of response depends mostly on the kind of doping anions used and the polarization potential applied during measurements. This detection can be utilized for design of amperometric biosensors for urea.
Detection of DNA hybridization using self‐assembled bilayer lipid membranes (BLMs)
Authors: Siontorou Christina G. , Nikolelis Dimitrios P. , Piunno Paul A. E. , Krull Ulrich J. 
Published: May 2005

AbstractThe present work reports the use of self assembled bilayer lipid membranes supported on the surface of a metal (s‐BLMs) as transducers for the direct electrochemical monitoring of DNA hybridization. Characterized oligomers based on single stranded deoxyribonucleic acid (ssDNA) thymidylic acid icosanucleotides that were terminated with C16 (dT20‐C16) and deoxyadenylic acid icosanucleotides (dA20) were used for the hybridization procedure at the lipid membrane surface. The decrease of the ion conductivity observed during the hybridization procedure is indicative of the formation of the duplex, which may subsequently be excluded from the membrane. The incorporation of nucleic acids into the lipid matrix was investigated by differential scanning calorimetric (DSC) experiments. The present simple electrochemical biosensor for monitoring of DNA hybridization was regenerable for multiple cycles of application. This approach provides low detection limits for DNA (a few hundreds of fmol), fast response times (on the order of a few minutes), mild conditions of hybridization and capability of analyzing small volumes of sample.
Electropolymerization of pyrrole‐2‐carboxylic acid and 4,4′‐dihydroxybenzophenone on platinum electrodes. Applications to assemble novel glucose sensors
Authors: Curulli A. , Palleschi G. 
Published: May 2005

AbstractThe electropolymerization of pyrrole‐2‐carboxylic acid (PY‐2‐COOH) and of 4,4′‐dihydroxybenzophenone (DHB) has been carried out on Pt electrodes by scanning the potential from +0.4 V to + 1.4 V (vs. SCE) for PY‐2‐COOH and from 0.0 V to + 0.8 V (vs. SCE) for DHB, at scan rate of 2–5 mV/s, in phosphate buffer (PBS) pH 8. To test the permselectivity of these polymers, cyclic voltammograms of H2O2, ascorbic acid (AA), uric acid (UA) and acetaminophen (APAP) were carried out and results were compared with those obtained at the bare electrode. The electropolymerization in the presence of glucose oxidase was also carried out. The probes were then tested as glucose sensors. Glucose was detected, by amperometric measurements at +0.6 V (vs. SCE). The linear response to glucose was in the range 7 × 10−6‐1.8 × 10−3 mol/L, for the sensor prepared with PPY‐2‐COOH and 4 × 10−6 −2 × 10−3 mol/L, for the sensor prepared with PDHB. The detection limit was 5 × 10−6 mol/L. for PPY‐2‐COOH and 2 × 10−6 mol/L for PDHB. The response time of both polymers was 3–5 s. The stability of the electropolymerized films and the glucose probes was evaluated, in storage and operational conditions The glucose probes, stored in buffer at 4°C when not in use, showed a residual enzyme activity of 50%, after about two months.
Sensor–analyte interaction kinetics as a metal speciation criterion
Authors: Labuda Ján , Bučková Miriam , Halamová L'udmila 
Published: May 2005

AbstractA general approach to the determination of metal speciation based on the initial reaction rate of the (bio)chemical sensor‐metal complex interaction is reported. The kinetic lability of the copper complexes with glycine, salicylic acid, humic acid, cysteine, thiourea and EDTA has been evaluated according to criteria based on the calculated and experimentally obtained rate constants for the accumulation of copper ions on a carbon paste electrode modified by the cation exchange resin Dowex 50W‐X8. Anodic stripping voltammetry was used for the copper quantification.
Voltammetric behavior of nitroimidazoles at a DNA‐biosensor
Authors: Brett Ana Maria Oliveira , Serrano Sílvia H. P. , Gutz Ivano , La‐Scalea Mauro A. , Cruz Maria Luiza 
Published: May 2005

AbstractThe newly developed DNA‐biosensor is a very promising tool for the investigation and study of the action of drugs specifically designed to interact with DNA. In this work the electrochemical reduction of nitroimidazole drugs was studied in the presence of DNA immobilized onto the surface of a glassy carbon electrode. This enabled preconcentration of the drug onto the electrode surface, which was then electrochemically reduced to the corresponding hydroxylamine which followed by reoxidation give the nitroso compound and subsequently an azoxycompound. Moreover, as the target of the nitroimidazole action was the DNA, the damage caused to DNA on the electrode surface by areduction product of this drug could be detected in situ.
Evaluation of copper‐based electrodes for the analysis of aminoglycoside antibiotics by CE‐EC
Authors: Voegel Phillip D. , Baldwin Richard P. 
Published: May 2005

AbstractAminoglycoside antibiotics including gentamicin, bekanamycin, tobramycin, lincomycin, neomycin, kanamycin, and ribostamycin have been determined by CE‐EC with copper clectrodes. Both copper wall‐jet electrodes (WJEs) and copper on‐capillary electrodes (OCEs) were evaluated. The OCEs provided μM detection limits, superior stability and reproducibility (2–3% relative standard deviation in oxidation current), and a simple instrumental set‐up without the need for capillary/electrode alignment. The analytical capabilities of the Cu‐OCE were examined, following the optimization of CE conditions, for the seven aminoglycosides above; and the practical utility of this approach was demonstrated through the determination of aminoglycoside antibiotics in three pharmaceutical preparations.
A bienzyme sensor for the determination of hypoxanthine and inosine
Authors: Hu Shengshui , Liu Chung‐Chiun 
Published: May 2005

AbstractA biosensor for the detection of hypoxanthine (Hx) and inosine (HxR) has been developed by the coimmobilization of nucleoside phosphorylase (NP) and xanthine oxidase (XO) on a chemically modified electrode, which uses a glassy carbon electrode coated with a Nafion ‐ paraquat film. This sensor responds to Hx and HxR in the presence of phosphate, and it responds only to Hx in the absence of phosphate (borate buffer as medium). The sensor measurement is based on the oxygen consumed due to the enzymatic reaction involving xanthine oxidase which is immobilized on the electrode surface. In this study, the experimental parameters are optimized and the linear relationships between the decreased currents and the concentrations of both Hx and HxR in the range of 1 × 10−6‐2 × 10−4M are obtained. This biosensor exhibits a high degree of sensitivity and can be used for the assay for Hx and HxR in fish meat or other biological samples.
What makes the anodic stripping voltammetry of mercury at a trace level possible?
Authors: Lovrić Milivoj , Scholz Fritz 
Published: May 2005

AbstractFor thermodynamic reasons it is impossible to describe the anodic stripping voltammetry (ASV) of mercury at concentrations below 10−7 mol/L as involving a simple deposition and dissolution of metallic mercury. That follows from the finite solubility of elemental mercury in water at ambient temperature. Instead, it is a more or less strong adsorption of mercury atoms on the electrode surface which makes ASV possible. At these low concentrations, the atomic mercury in the solution can no longer be neglected. A theoretical description for staircase cyclic voltammetry of the reaction Hg ⇌ Hg ⇌ Hg + 2e− has been developed and it is discussed with respect to the ASV of mercury. The adsorption of atomic mercury is considered for the case of different electrode materials and adsorption constants have been estimated from underpotential deposition peaks. The distribution of the following mercury species is given for different electrode potentials and total mercury concentrations: Hg, Hg2+, Hg, Hg and Hg.
Conducting phenylenevinylene blends as electrode materials in LC amperometric detection
Authors: Staes E. , Nagels L. J. , Verreyt G. , Jacobs S. , Bao Y. , Geise H. J. 
Published: May 2005

AbstractA novel amperometric electrode based on a conducting polymer is presented and its properties are compared with those of a glassy carbon electrode. The electrode material was made by mixing 2,5‐dimethoxy‐1,4‐bis[2‐(3,4,5‐trimethoxy‐phenyl)ethenyl]benzene with iodine and polycarbonate. The blend was coated on a glassy carbon electrode by evaporation from a chloroform solution. Catecholamines were used as test substances in LC and FIA measurements. They were oxidized at a potential of +0.7 V (vs. SCE). The electrode exhibited a linear response for injected concentrations from 2.5 × 10−6M to 2.5 × 10−3M. It had a response time of 1.2 s and a coulometric efficiency of 0.74% at a linear flow rate of 1 mL/min. The electrode material is stable for several months under normal operating conditions. Hydrodynamic voltammograms showed E1/2 values shifted by approximately 100 mV as compared to glassy carbon. The novel redox‐conducting coating is proposed as an alternative material for the development of enzyme electrodes and chemically modified electrodes.
Voltammetric study of nimesulide and its differential pulse polarographic determination in pharmaceuticals
Authors: Álvarez‐Lueje A. , Vásquez P. , Núñez‐Vergara L. J. , Squella J. A. 
Published: May 2005

AbstractNimesulide, N‐(4‐nitro‐2‐phenoxyphenyl)methanesulfonamide is an antiinflamatory analgesic agent that is both reducible at the mercury electrode and oxidizable at the glassy carbon electrode. Nimesulide in hydroalcoholic solution, presents cathodic response in a wide range of pH (2–12), both, by differential pulse and tast polarography techniques. The obtained results show only one main well‐defined peak or wave in all the pH range studied. This peak (or wave) corresponds to the nitro group reduction in position 4. The voltammetric oxidation shows one well‐resolved signal in all the pH range studied. This anodic signal could be attributed to the methylsulfonamide group oxidation. For analytical purposes, a very well resolved diffusion controlled differential pulse polarographic peak obtained at pH 7 was selected. This peak was used to develop a new method for the determination of nimesulide in pharmaceutical dosage forms. The recovery study (104.8% with a RSD of 1.3%) shows that the method is sufficiently accurate and precise to be applied in the individual tablet assay of commercial samples.
Spontaneous assembly of the inclusion complexes of viologen‐attached alkanethiols and α‐, β‐cyclodextrin on gold electrode
Authors: Yan Juchao , Dong Shaojun 
Published: May 2005

AbstractElectroactive self‐assembled monolayers (SAMs) with well‐defined electrochemical responses were prepared by spontaneous assembly of the inclusion complexes (CD/C8VCωSH) of viologen‐attached alkanethiols (C8VCωSH) and α‐ and β‐cyclodextrin (CD). They were characterized by X‐ray photoelectron spectroscopy and cyclic voltammetry. The results demonstrate that the chemisorption process of CD/C8VCωSH on gold substrate occurs through S–Au bonds, and that the redox sites in SAMs of CD/C8VCωSH are in a much more uniform environment than those in SAMs of C8VCωSH.
Simultaneous adsorptive stripping voltammetric measurements of trace chromium, uranium, and iron in the presence of cupferron
Authors: Wang Joseph , Lu Jianmin , Luo Denbai , Wang Jianyan , Tian Baomin 
Published: May 2005

AbstractThe ligand cupferron is used for the simultaneous adsorptive stripping voltammetric measurements of several trace metals. Experimental variables affecting such multielement capability, including the cupferron concentration, adsorption time or metal concentration are explored. Adequate resolution is demonstrated for up to five metals (FeIII, UVI, CrVI, VV, and BiIII), present at the ppb concentration level. Possible changes in peak heights, associated with competition for the complexing ligand and/or coadsorption effects, are explored. Different concentration ratios of the mixture components can be tolerated. Applicability to groundwater or river‐water samples is illustrated.
A novel amperometric transducer design for needle‐type implantable biosensor applications
Authors: Yang Qingling , Atanasov Plamen , Wilkins Ebtisam 
Published: May 2005

AbstractA novel transducer design is proposed based on a electrocatalyst for hydrogen peroxide oxidation (platinum black) electrodeposited on the inner wall of a stainless steel needle which serves as a working electrode, and an external Ag/AgCI reference/counter electrode. Electropolymerized 1,3‐diaminobenezene (1,3‐phenylenediamine) is employed as a protective layer for the platinum black as well as an interference eliminating layer. This configuration uses the Pt electrocatalyst in its most active dispersed form and ensures good mechanical ruggedness and protection of the catalytic and biological components. The design also provides the possibility to obtain high enzyme loading and hence an extended sensor life‐time. Two types of glucose sensors were constructed based on this novel design concept. The enzyme (glucose oxidase) was immobilized either in a hydrophilic gel matrix inside the needle body (i) or cross‐linked on the inner needle surface (ii). Cellulose triacetate, polycarbonate, and Nafior were used as external diffusion control layers, which extended the linear range of the sensor response to over 25 mM glucose. These biosensors demonstrated diminished response to interferences from oxidizable compounds present in body fluids and a life time of at least three months.
Catalytic behavior of osmium(II), rhodium(III) and ruthenium(II) Phthalocyanines towards the electrooxidation of cysteine on glassy carbon electrodes
Authors: Sekota Mantoa , Nyokong Tebello 
Published: May 2005

AbstractGlassy carbon electrodes (GCE's) modified with phthalocyanine complexes of Rh, Ru and Os are employed for the catalytic oxidation of cysteine. When cyanide and dimethylsulfoxide (DMSO) are used as axial ligands giving (DMSO)(Cl)RhIIIPc, [(CN)2RhIIIPc]−, (DMSO)2OsPcII, and [(DMSO)2Ru(II)Pc]·2DMSO complexes, the peak currents for the oxidation of cysteine increase after each scan, indicating an increase in the catalytic activity of the electrode with repetitive scanning. This improvement in the catalytic activity of the GCE after the first scan is attributed to the formation of dimeric π cation radical species at the electrode surface.
Determination of gold by anodic stripping voltammetry with carbon fiber ultramicroelectrodes
Authors: Alarnes‐Varela Gabriel , Costa‐García Agustín 
Published: May 2005

AbstractCarbon fiber ultramicroelectrodes have been used in anodic stripping voltammetry (ASV) of trace gold. The advantageous characteristics of ultramicroelectrodes combined with ASV resulted in a fast, selective, sensitive and reproducible method. An electrochemical pretreatment was necessary for analytical determinations. The combination of supporting electrolyte (HCl 0.1 M) and electrodeposition potential (0.0 V) gave a high selectivity. A calibration plot from 1.00 × 10−8 M to 1.60 × 10−6 M (r = 0.9994) was achieved with a detection limit of 5.94 × 10−9 M and a relative standard deviation (RSD) of 2.87% at 3.0 × 10−7 M. AgI, CuII, PbII and HgII metals in the concentration of 1.00 × 10−6 M were not found to interfere with the ASV of gold (3.00 × 10−7 M) when carried out under optimum conditions. The procedure was applied to the determination of gold in two tap water synthetic samples.
Determination of thioglycolic acid and cysteine in hair‐treatment products at ceramic carbon composite electrodes
Authors: Wang Lai‐Hao , Chen Zong‐Shion 
Published: May 2005

AbstractCeramic carbon composite electrodes, prepared by incorporating ceramic powders with carbon paste matrices, are shown to facilitate the oxidation of thiol compounds. These electrooxidation processes are applied for the detection of cysteine and thioglycolic acid in hair‐treatment products.