bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative studies between ion‐selective field effect transistors and ion‐selective electrodes with polymeric membranes
Authors: Miyahara Yuji , Simon Wilhelm 
Published: May 2005

AbstractCharacteristics of ion‐selective field effect transistors (ISFETs) and ion‐selective electrodes (ISEs) with solvent polymeric membranes were compared for slope, selectivity, drift, and hysteresis. Drift and hysteresis of ISFETs were significantly inferior to those of analogous ISEs. Experiments using conventional ISEs with internal electrolyte solutions and ion‐selective liquid membranes of different kinds indicate that both primary ion and ionophore are necessary in the internal electrolyte solution and the ion‐selective membrane, respectively, to achieve small drift and small hysteresis. It is, therefore, concluded that to realize highly reliable membrane‐solid contact devices, the interface between the membrane and the solid in membrane–solid contact devices like ISFETs and coated wire electrodes (CWEs) should be electrochemically defined.
Determination of some metal ions using lichen‐modified carbon paste electrodes
Authors: Connor Michelle , Dempsey Eithne , Smyth Malcolm R. , Richardson David H. S. 
Published: May 2005

AbstractLichens have long been used as biomonitors of environmental pollution. We therefore investigated the application of lichen‐modified carbon paste electrodes (CPEs) for the determination of lead(II) and copper(II) using differential pulse anodic stripping voltammetry. These electrochemical biosensors incorporate the biological selectivity of lichen species such as Cladonia portentosa and Lobaria pulmonaria, and the genus Roccella, with the sensitivity of electrochemical detection. As such, they may offer new reactivity patterns that could be exploited in the determination of trace metal ions in environmental samples and in speciation studies. The voltammetric responses were evaluated with respect to pH of accumulation (carried out under open circuit conditions), pH of electrolyte, solution, metal ion concentration, percentage lichen loading in the carbon paste, interferences, and surface renewal.
Comparison of adsorptive stripping voltammetry at mercury and carbon paste electrodes for the determination of ciprofloxacin in urine
Authors: O'Dea Philip , Garcíc Agustín Costa , Ordieres Arturo J. Miranda , Blanco Paulino Tuñón , Smyth Malcolm R. 
Published: May 2005

AbstractWe compared hanging mercury drop electrodes (HMDEs) and carbon paste electrodes (CPEs) for the determination by adsorptive stripping voltammetry (AdSV) of the antibiotic ciprofloxacin in urine. The antibiotic compound could be preconcentrated at both electrode surfaces, with carbon paste electrode yielding a better performance. These electrodes could be used to determine between 6 × 10−7 and 4 × 10−6 M ciprofloxacin in urine. A cleanup procedure (with 81% recovery), utilizing a C18 Sep Pak cartridge, was required to separate ciprofloxacin from the biological matrix prior to adsorptive stripping analysis. The method was applied to the determination of ciprofloxacin in spiked urine samples with a relative standard deviation of 4.1%.
Coated wire electrodes in the analysis of surfactants of various types: An overview
Authors: Vytřas Karel 
Published: May 2005

AbstractSimple ion‐selective electrodes of the coated wire type were prepared using an ordinary aluminum wire conductor, coating the central wire with the membrane formed by plasticized poly vinyl chloride. These simple and inexpensive electrodes can be used advantageously as sensors in ion pair formation‐based titrations of surfactants of various types. Cationic surfactants are titrated using sodium tetraphenylborate titrant yielding titration curves with sharp potential breaks. For the determination of nonionic surfactants containing poly oxyalkylene chains, the method used was based on the precipitation of ternary compounds with sodium tetraphenylborate in the presence of bivalent metal ion with an ionic radius higher than 100 pm. Also ampholytic surfactants can be titrated directly with tetraphenylborate in acidic solutions, in which they are cationic; but for the determination of some of them, back‐titration is more convenient. Anionic surfactants are titrated using lipophilic cationic titrants such as quaternary ammonium or pyridinium salts. Some mixed systems can also be analyzed. Several examples are given.
Study of the adsorptive stripping square‐wave voltammetry of bovine serum albumin
Authors: Flores J. Rodríguez , Marín C. , Gonzalez E. , Pariente F. , Lorenzo E. 
Published: May 2005

AbstractThe adsorptive stripping square‐wave voltammetric behavior of bovine serum albumin (BSA) is described. Conditions were optimized for the determination of this protein with respect to accumulation potential, accumulation time, drop size, scan rate, frequency value, and electrolyte concentration. Under these optimum conditions for the determination of BSA, two calibration plots were obtained. For an accumulation time of 60 seconds, the plot was linear in the range 0.25–1.25 μg/mL of BSA (r = 0.997); for an accumulation time of 180 seconds, the linear range was 0.10–1.25 μg/mL of BSA (r = 0.997). The square‐wave procedure offers the advantages of speed, higher sensitivity for the determination of BSA, and the discrimination against background currents. This method was applied successfully for the determination of total protein in fetal calf serum.
Electrochemical study and determination of todralazine by adsorptive stripping voltammetry
Authors: de Balugera Z. Gomez , Barrio R. J. , Goicolea A. , Arranz J. F. 
Published: May 2005

AbstractThe electrochemical reduction and adsorption of todralazine on the hanging mercury drop electrode are explored. These properties allow the development of a sensitive adsorptive stripping voltammetric procedure, with a detection limit of 3.2 × 10−9 mol L−1. A method is proposed for rapid determination in commercial preparations and human serum.
Electrochemical detection of todralazine in high‐performance liquid chromatography
Authors: Barrio R. J. , de Balugera Z. Gomez , Arranz J. F. , Goicolea A. 
Published: May 2005

AbstractThe electrochemical behavior of todralazine was studied by cyclic voltammetry on a glassy carbon electrode at different pH values. The results obtained were used in the electrochemical detection of todralazine in chromatographic effluents. The optimum detection potential was 0.90 V (vs. SCE). The limit of detection was 0.36 μg/L and the limit of determination 4.8 μg/L. The method can be applied to the determination of todralazine in human serum It offers significant advantages in sensitivity, specificity, and accuracy with respect to other reported methods.
Electrochemical behavior of tizanidine at the mercury electrode I. Reduction mechanism and surface state study
Authors: Quarin G. , Viré J.‐C. , Patriarche G. J. , Ruiz B. Lope , Christian G. D. 
Published: May 2005

AbstractThe electrochemical behavior of Tizanidine has been studied using dc, ac, and pulse polarographic techniques. Reduction of the compound occurs through an electrochemical mechanism involving a six‐electron transfer. Autoinhibition of the process resulting from the adsorption of species affects the reduction rate constants. At the electrode surface, adsorption proceeds through a competition between the oxidized and reduced forms.
Amperometric operation of porous flow‐through electrodes at very low conversion efficiencies in flow stream detectors
Authors: Zhu Caobin , Curran David J. 
Published: May 2005

AbstractThe limiting current equation for a porous flow‐through electrode operated amperometrically at low conversion efficiencies can be expressed in the same general format as that for amperometric detectors of other types. The equation shows that a critical dimension for the porous electrode is the pore diameter, the limiting current being inversely proportional to the two‐thirds, power of the pore radius. Experimental verification was obtained using reticulated vitreous carbon (RVC) electrodes.
Anodic stripping voltammetry in highly‐resistive media by electrodes supported on ion‐exchange membranes
Authors: Schiavon Gilberto , Zotti Gianni , Toniolo Rosanw , Bontempelli Gino 
Published: May 2005

AbstractAn electroanalytical device is described that is suitable for trace metal analysis by anodic stripping voltammetry (ASV) in highly‐resistive media in the absence of supporting electrolytes. It consists of a thin mercury film electrodeposited at the glassy carbon‐ion‐exchange membrane interface obtained by clamping a glassy carbon ring to one surface of a perfluorinated ion‐exchange membrane (cationic, Nafion 117, or anionic, Tosflex IE SA48). The inner surface of the membrane is in contact with an electrolyte solution (0.01 M HClO4), containing the counter and reference electrodes. The ion‐exchange membrane replaces a conventional supporting electrolyte dissolved in the analyte sample and can be regarded as a solid polymer electrolyte (SPE) confined to the near neighborhood of the working electrode. This device has been used to perform differential pulse anodic stripping voltammetric (DPASV) analyses of electrolyte‐free aqueous synthetic samples containing copper and lead ions. Better results are found at glassy carbon‐supported mercury electrodes facing anionic Tosflex membranes, since similar devices assembled with cationic Nafion membranes experience a memory effect associated with blockage of metal ions, due to cation‐exchange processes that occur during the stripping redissolution step, even though these processes are able, at the same time, to lead to an increase of DPASV peaks due to metal ion accumulation near the electrode surface. Approximate detection limits of 3.5 × 10−10 M (0.02 ppb) for Cu2+ and 3 × 10−10 M (0.05 ppb) for Pb2+ are estimated at Tosflex‐equipped devices for a signal‐to‐noise ratio of 3. Possible modifications aimed at improving the performance of such a device are discussed.
A Potentiometric approach to the study of the antagonism between acetazolamide and I‐carnitine congeners on carbonic anhydrase activity
Authors: Botré Claudio , Botré Francesco , Pranzoni Cinzia 
Published: May 2005

AbstractThe in vitro interactions among carbonic anhydrase (CA), acetazolamide (ACTZ), and some short chain acylcarnitines (l‐ and d‐isomers) were studied by means of a recently developed potentiometric method of analysis, based on a pCO2 sensor. The l‐ and d‐isomers of carnitine (C), acetylcarnitine (AC), propionylcarnitine (PC), and isobutyrrylcarnitine (iBC) were found not to affect CA catalytic activity in the absence of other compounds. Upon testing in the presence of ACTZ, the i‐isomers of the carnitine congeners were shown to antagonize the chemical inhibition of carbonic anhydrase II from bovine erythrocytes, whereas in this case the d‐isomers did not show any effect. The results obtained in these experiments, carried out at 25 and at 37°C, confirm the high reliability of this new approach and highlight the positive effect of l‐carnitine congeners on CA catalytic activity. The potentiometric method should be suitable for monitoring the interaction of other enzymes and CA.
Electrochemical transducers for in vivo monitoring
Authors: Vadgama Pankaj , Desai Mohamed , Crump Paul 
Published: May 2005

AbstractElectrochemical sensors have seen extensive development in recent years, particularly with regard to their use in biological fluids. Their facility for near‐reagentless assay, together with an ability to generate a continuous signal, has made them an ideal choice for in vivo monitoring. Both Amperometric and potentiometric devices have been fabricated for practical monitoring. Ions, gases, and metabolites have been assayed, thereby providing useful biological and clinical insights. This view provides a description of the major types of electrochemical sensors used in vivo, together with some of the problems associated with their biological interfacing for both extracorporeal and invasive monitoring.
The voltammetric response of ethanolamine at gold electrodes in alkaline media
Authors: Jackson Warren A. , Lacourse William R. , Dobberpuhl David , Johnson Dennis C. 
Published: May 2005

AbstractVoltammetric data are described that were obtained at Au electrodes in 0.1 M NaOH for ethanolamine and related compounds using a rotated disk electrode (RDE) and a thin‐layer electrochemical cell (TLEC). The anodic signal for the alcohol group of ethanolamine is much greater than for ethanol at the same concentration. This is attributed to the benefit of pre‐adsorption by the amine group of ethanolamine on the Au surface. Oxidation of the alcohol group of ethanolamine is terminated by formation of surface oxide. However, oxide formation appears to catalyze oxidation of the amine groups of ethanolamine and ethylamine. A value of n = ca. 4.6 eq mol−1 was determined for oxidation of the alcohol group of ethanolamine by exhaustive electrolysis in the TLEC. Glycine is tentatively concluded to be an oxidation product on the basis of n and the result of a chromatographic analysis of the contents of the TLEC following electrolysis at 0.0 V vs. SCE.
A redox‐active polymer film mediated enzyme electrode for amperometric determination of free cholesterol
Authors: Oyama Noboru , Ikeda Shin , Suzuki Mikiko , Ohsaka Takeo 
Published: May 2005

AbstractA new amperometric sensor for determination of free cholesterol based on a bilayer‐film coating has been fabricated and its sensor characteristics have been examined by cyclic voltammetry and under steady‐state conditions. The electrode substrate was coated with two kinds of polymeric films in a bilayer state, i.e., first with the redox‐active cobalt tetrakis(o‐aminophenyl)prophyrin polymer (poly‐CoTAPP), and then with the enzyme film consisting of bovine serum albumin and cholesterol oxidase (CHOx). In this sensor system for assay of free cholesterol, oxygen consumption could be monitored by measuring the current for oxygen reduction electrocatalyzed by the inner poly‐CoTAPP film according to the following reaction sequence:magnified imagewhere reactions 1, 2, and 3 correspond to the cholesterol–cholesterol oxidase enzymatic‐reaction, the electrocatalytic reduction of O2 by the poly‐CoTAPP film, and the electrode reaction of Co(III/II)TAPP couple in the poly‐CoTAPP film, respectively. The reproducible relationship between concentration of free cholesterol and sensor output was obtained. The sensitivity and the dynamic range were found to depend on the amount of CHOx confined in the enzyme film.
Lead ion sensitive electrode based on a supported BLM system
Authors: Salamon Zdzislaw , Ti Tien H. 
Published: May 2005

AbstractThe lead ion sensitivity of a solid‐supported BLM system containing TCNQ (7, 7, 8, 8‐tetracy‐anoquinodimethan) as an electron mediator in 4, 4′‐n‐octyl‐cyanobiphenyl (8CB) dissolved in squalene, with a teflon coated platinum wire as a solid support, has been investigated with cyclic voltammetry. The results have shown that TCNQ in a cyanobiphenyl bilayer membrane produces a unique System that increases by three orders of magnitude the lead ion sensitivity of the platinum electrode. Cyclic voltammograms have also shown that a charge‐transfer complex between liquid crystal and TCNQ molecules is created and participates in redox reactions.
Amperometric detection of sugars in food at a nafion‐copper modified electrode
Authors: Mannino Saverio , Rossi Margherita , Ratti Simona 
Published: May 2005

AbstractThe characteristics and applicability of a Nafion‐copper modified electrode for the determination of some sugars in food samples are described. Coating with a Nafion membrane and subsequent immersion in a copper solution provides a good barrier against many electroactive hydroxyacids commonly found in food samples. The Nafion modified electrode is stable, can be easily renewed, and shows reproducible results. The analytical utility of the polymer‐coated electrode is demonstrated by application to wine and milk samples.
Enzyme‐modified carbon paste: Tetrathiafulvalene electrodes for the determination of acetylcholine
Authors: Hale P. D. , Liu L.‐F. , Skotheim T. A. 
Published: May 2005

AbstractThe response characteristics of a new sensor for determining acetylcholine are reported. The sensor is based on a carbon paste electrode containing the enzymes acetylcholinesterase and choline oxidase and the electron transfer mediator tetrathiafulvalene (TTF). TTF is shown to efficiently reoxidize the reduced flavin adenine dinucleotide centers of choline oxidase. Acetylcholine calibration graphs are obtained in the range 10−6 to 10−3 M in pH 7.0 phosphate buffer, and the sensors are shown to operate efficiently at low applied potentials, where electrochemical interference due to oxidation of ascorbic acid is minimized.
Langmuir–blodgett films of doxyl‐stearic acids: Cyclic voltammetry
Authors: Richardson T. , Roberts G. G. , Barghout R. , Compton R. G. , Riley D. J. 
Published: May 2005

AbstractThe electrochemical oxidation of Langmuir–Blodgett films of n‐doxyl‐stearates (n = 5, 7, 12, 16; present as their cadmium salts) on indium tin oxide electrodes has been studied. The n = 12 species gives cyclic voltammograms (CVs) that reveal split peaks consistent with the formation of an ordered partially oxidized layer with a structure controlled by interactions of longer range than nearest neighbor.
Batch injection analysis with the rotating disk electrode
Authors: Chen Liang , Wang Joseph , Angnes Lucio 
Published: May 2005

AbstractThe use of the rotating disk electrode (RDE) for batch injection analysis (BIA) is illustrated. The technique involves injections of microliter samples into a large‐volume blank solution, at a fixed location below the disk center. Transient response peaks—similar to those of flow injection analysis—are observed, reflecting the transport of the sample plug toward and away from the RDE. The effects of various experimental variables on the BIA/RDE operation are described. Injection rates of several thousand samples per hour can be achieved, with relative standard deviations of 1–3%, and detection limits at the micromolar (ng) level.
Separation and identification of isoflavones with on‐line liquid chromatography‐electrochemistry‐thermospray mass spectrometry
Authors: Dewald Howard D. , Worst Sue Anne , Butcher Jared A. , Saulinskas Elaine F. 
Published: May 2005

AbstractThe on‐line high‐performance liquid chromatography‐electrochemistry‐thermospray mass spectrometry (LCEC‐LC/MS) for separation and identification of the phenolic isoflavones genistein, formononetin, and Biochanin A is described. The isoflavones are separated on a C‐18 reversed phase column with methanol: 0.1 M ammonium acetate pH (70:30 v/v) as eluent, which is compatible for both LCEC and LC/MS detection. Low ng detection is achieved with a conventional glassy carbon thin‐layer electrochemical cell at 1.3 V vs. Ag/AgCl. Selected ion monitoring (SIM) mode LCMS results in detection levels at the 20–50 ng range, and the compounds are positively identified. In the on‐line detection, the electrochemical cell is connected to the thermospray and the column effluent flows from the working electrode into the heated thermospray capillary tube. The results show that on‐line coupling between a thin‐layer LCEC and a thermospray‐LC/MS can be used to characterize analytical systems.
Trace determination of antimony and bismuth in snow and water samples by stripping voltammetry
Authors: Postupolski Andrzej , Golimowski Jerzy 
Published: May 2005

AbstractSimultaneous determination of antimony and bismuth was performed from 0.5 M HCl solution that contained 0.1 M hydrazine, using the hanging mercury electrode by differential pulse anodic stripping voltammetry with very slow potential scan rate and small pulse amplitude. The influence of HCl and chloride concentrations on the peak shape of Bi and Sb and the influence of other ions and organic substances were investigated. For the determination of antimony and bismuth in water and snow samples, the UV irradiation and the reduction of Sb(V) to SE(III) by hydrazine in boiling solution were applied. The detection limit for Bi and Sb is 20 ng L−1.
An XPS investigation of silver bromide‐coated ion‐selective electrodes
Authors: Strydom C. A. , Van Staden J. F. , Strydom H. J. 
Published: May 2005

AbstractXPS data of AgBr‐coated ion‐selective electrodes exposed to high concentrations of Ag+, Cl−, Br−, I−, and NH3revealed a change in the surface properties of the original electrode. A 40 min to one week exposure of the silver bromide ion‐selective electrode surface to solutions containing high concentrations of chloride ions leads to the formation of a mixed halide layer, as the chloride ions are incorporated in the surface. Exposure to high concentrations of iodide‐containing solutions results in a new silver iodide layer on top of the original silver bromide laver. Silver ions diffuse to the newly formed layers. NH3results in the rapid degradation of the AgBr surface as the diamine complex, Ag(NH3)+2, is formed.
Spectroelectrochemistry of phenylnitromethane on gold and silver electrodes
Authors: Holze Rudolf 
Published: May 2005

AbstractThe spectroelectrochemical behavior of phenylnitromethane (nitromethylbenzene) dissolved in neutral and acidic electrolyte solutions at gold and silver electrodes is described. Observed cyclovoltammetric peaks are attributed to the reduction of the nitro group. Surface Enhanced Raman spectra (SERS) of adsorbed molecules are interpreted based on an assignment of the Raman band of the free PNM using literature data. A coordination via the oxygen atoms of the nitro‐group and consequently a tilted or perpendicular orientation of the adsorbed molecule with respect to the electrode surface are concluded.
Adsorptive stripping voltammetry for determination of trace amounts of aluminum with calmagite
Authors: Stryjewska Ewa , Rubel Stanislaw 
Published: May 2005

AbstractExperimental parameters for determination of aluminum (up to 15 ppb) were evaluated in acetate (pH = 4.2) and borate (pH = 8.9) buffer solutions. Because the reaction of Calmagite in acetate buffer requires heating (10 min, 90°C) the total analysis time is relatively long. This inconvenience is circumvented by using a borate buffer. The complexation reaction is nonspecific in both media. Iron(III) should be reduced using hydroxylamine hydrochloride, whereas copper(II) and some other metals may be eliminated by electrolysis. The developed method was used for aluminum determination in reference material—flour V‐8 (IAEA‐Vienna), tap water, and commercial 4% acetic acid before and after boiling in an aluminum pot.
Determination of glutamine in serum using an amperometric enzyme electrode
Authors: Villarta Rhodora L. , Palleschi Giuseppe , Suleiman Ahmad , Guilbault George G. 
Published: May 2005

AbstractAn amperometric enzyme electrode for the determination of L‐glutamine was developed. The probe consisted of a platinum electrode that senses hydrogen peroxide produced from the reactions catalyzed by glutaminase and glutamate oxidase, which are co‐immobilized on a preactivated Immobilon‐AV Affinity membrane. Protective membranes eliminated interferences from L‐glutamate and most compounds electroactive at a similar potential. The response of the probe was linear over the concentration range 1 × 10−6 M to 7.5 × 10−4 M. L‐Glutamine in serum samples obtained from healthy volunteers was determined using the probe, and the results correlated well with previously reported values.