Showing papers on "Polarography published in 1986"
TL;DR: The first membrane-covered oxygen electrode had both the anode and cathode behind a nonconductive polyethylene membrane, making possible quantitative measurements of oxygen tension in blood, solutions, or gases.
Abstract: The electrochemical reduction of oxygen was discovered by Heinrich Danneel and Walther Nernst in 1897. Polarography using dropping mercury was discovered accidentally by Jaroslav Heyrovsky in Prague in 1922. This method produced the first measured oxygen tension values in plasma and blood in the 1940s. Brink, Davies, and Bronk implanted platinum electrodes in tissue to study oxygen supply, or availability, from about 1940, but these bare electrodes became poisoned when immersed in blood. Leland Clark sealed a platinum cathode in glass and covered it first with cellophane; he then tested silastic and polyethylene membranes. In 1954 Clark conceived and constructed the first membrane-covered oxygen electrode having both the anode and cathode behind a nonconductive polyethylene membrane. The limited permeability of polyethylene to oxygen reduced depletion of oxygen from the sample, making possible quantitative measurements of oxygen tension in blood, solutions, or gases. This invention led to the introduction of modern blood gas apparatus.
72 citations
TL;DR: In this paper, a potentiel de l'electrode Ag/ion Ag +, 0,01 mol. dm −3, dans des solvants non aqueux vs bis-(biphenyl) chrome (I)/(0) en vue d'elucider l'effet du solvant sur les proprietes redox
Abstract: Utilisation des potentiels de demi-vague des ions des metaux alcalins et Tl + , Cu + , Ag + , Zn 2+ , Cd 2+ , Cu 2+ et Pb 2+ , ainsi que du potentiel de l'electrode Ag/ion Ag + , 0,01 mol. dm −3 , dans des solvants non aqueux vs bis-(biphenyl) chrome (I)/(0) en vue d'elucider l'effet du solvant sur les proprietes redox
69 citations
TL;DR: In this article, the potentiometric and spectroscopic results for Cu(II), Ni(II) and Co(II)-D-glucosamine ion complexes with D- glucosamine and the polarographic results for C-II-Dglucosa systems are discussed.
64 citations
TL;DR: In this paper, the electrochemical behavior of Ni(II) on the mercury electrode in the presence of dimethylglyoxime was investigated in weakly alkaline media by different techniques.
64 citations
TL;DR: In this article, the half-wave potentials, ΔV 1 2, of the polarograms, which can be related directly to the transfer energies, are discussed on the basis of the ionic radii, crystallographic forms and charges of the anions.
59 citations
TL;DR: In this article, the reduction of chalcone at the dropping mercury electrode is expressed by scheme (A)−(U) with an approximate value p K 6 =10.2 and p K 9 =8.75.
55 citations
TL;DR: In this article, the authors used the step method to obtain voltammograms from peak heights, shlfts, and widths for various values of the thlckness parameter.
Abstract: The theoretlcal response for the appllcatlon of square wave voltammetry to a reversible system at the mercury fllm electrode Is derlved. Numerlcal calculatlons using the step method yield voltammograms from whkh peak heights, shlfts, and widths for various values of the thlckness parameter are obtained. This method produces results that agree wlth those of flnlte difference simulations but Is much faster. The differential current vdtammogram are symmetrical, shm toward more negative potentials wlth decreasing film thlckness parameter (an€,,/d log A = 59.2 mV), and dlsplay a maximum when the dlffuslon length of the reduced metal In the film equals the fllm thickness. For customary square-wave parameters of n€,, = 50 mV and nA€, = 10 mV the normallred peak height In the thin-film region (AGp = 1.500) Is larger than that obtained in the thkk-flh ihnlt (A$, = 1.312). Square wave direct voltammetry at mercury film electrodes affords rapid analysis times, dlscriminatlon against charglng current, enhanced sensltlvlty, and clear definition of peaks.
51 citations
TL;DR: Tetraphenylphosphonium chloride was shown to adsorb strongly on a hanging mercury drop electrode and to be amenable to determination by differential-pulse adsorptive stripping voltammetry, a useful reagent for partially identifying individual colouring matters even when they are present at very low concentrations.
Abstract: Sixteen food and two cosmetic synthetic colouring matters were shown to adsorb strongly on a hanging mercury drop electrode and to be amenable to determination by differential-pulse adsorptive stripping voltammetry. When a 2-min accumulation time was used, the increase in sensitivity over differential-pulse polarography at a dropping mercury electrode was between 8- and 100-fold, depending on the colouring matter determined. Using longer accumulation times, 1 × 10–10M concentrations of some food colours could be determined. The addition of tetraphenylphosphonium chloride shifted the reduction potentials of some colouring matters to more negative values and either decreased or increased the size of the peaks obtained. This makes it a useful reagent for partially identifying individual colouring matters even when they are present at very low concentrations. Increased sensitivity was obtained with carmoisine, tartrazine and quinoline yellow by its addition.Procedures for applying the method to the determination and partial identification of colouring matters in tablet coatings and in a lipstick have been developed. The need to dilute more concentrated sample solutions has the advantage of eliminating matrix effects, which are sometimes apparent when differential-pulse polarography is applied without dilution.
42 citations
TL;DR: The mechanism of potassium ion transfer from an aqueous to a 1,2-dichloroethane phase which is facilitated by urushiol crown ether or dibenzo-18-crown-6 in the range of potassium concentrations, cK+, from 0.1 mM to 1 M, was studied by current scan polarography at the ascending water electrode, chronopotentiometry, and chrono-physiometry with current reversal at the stationary water electrode as mentioned in this paper.
42 citations
TL;DR: In this paper, the electrochemical behavior of 1,1′-dimethyl-4,4′-bipyridinium dichloride (methyl viologen, MV) is complicated with the strong adsorption of both the oxidized (MV2+) and the reduced(MV+·) forms of MV on a mercury electrode.
Abstract: The electrochemical behavior of 1,1′-dimethyl-4,4′-bipyridinium dichloride (methyl viologen, MV) is complicated with the strong adsorption of both the oxidized (MV2+) and the reduced (MV+·) forms of MV on a mercury electrode. MV2+ adsorbs on the electrode with a flat orientation at more positive potentials than the potential of zero charge of the mercury electrode. MV+· adsorbs on the electrode with a vertical orientation at more negative potentials than the formal potential of the MV2+⁄+· couple, (E0′)MV. It is probable that the change in the orientation of the adsorbed MV+· from flat to vertical with the increase in the MV+· concentration in the vicinity of the (E0′)MV leads to a strongly attractive interaction between the adsorbed MV+· molecules and a sharp voltammetric adsorption peak results at higher concentrations of MV2+.
41 citations
TL;DR: In this article, the Cd:Se ratio of thin film from aqueous selenosulfite solution has been determined using polarography and Rutherford backscattering spectrometry (RBS).
Abstract: Cathodic electrodeposition of thin film from aqueous selenosulfite solution has been studied as a function of solution composition and electrode potential The Cd:Se ratio has been determined using polarography and Rutherford backscattering spectrometry (RBS) Polarography gives a composition averaged over the whole film (ca 3 cm2) while RBS gives local surface composition (1 mm2) The results of the two techniques agree within experimental error The average Cd:Se ratio was found to be close to 10 for a variety of conditions The effect of various deposition and annealing conditions on light to electrical power conversion efficiency are presented Cyclic voltammetry has been used to explore the mechanism for the deposition process
TL;DR: In this article, the simultaneous diffusion of different metal species with unequal diffusion coefficients in a metal complex system is considered, and a comprehensive account is given of the conditions under which the mean diffusion coefficient D is operative.
TL;DR: Ion-selective electrodes prepared by coating polymer films containing electroactive species have been incorporated on a metallic substrate and have proven to be effective for a wide variety of inorganic and organic anions and cations as discussed by the authors.
Abstract: Ion-selective electrodes prepared by coating polymer films containing electroactive species have been incorporated on a metallic substrate and have proven to be effective for a wide variety of inorganic and organic anions and cations. Their characteristics are reviewed here. In addition, current scan polarography and chronopotentiometry across an aqueous–immiscible organic solvent interface have been applied to the study of ion-transport processes, such as that involved in the potassium–crown ether ion-selective electrode systems. A mechanisms for such systems is described.
TL;DR: In this article, the electroreduction behavior of some substituted 1,1-dicyanoethylene derivatives in acetonitrile was investigated using the results of cyclic voltammetry, rotating disc voltammetric, dc and differential pulse polarography and controlled potential electrolysis experiments.
TL;DR: In this article, a simple d.c. polarographic method has been developed for the determination of metronidazole in dosages forms, which produces a well defined 4-electron polarographic wave followed by another wave of about half the height of the first wave.
Abstract: A simple d.c. polarographic method has been developed for the determination of metronidazole in dosages forms. In Robinson - Britton buffer (pH 4.38) and in presence of 1.60 × 10−3 % Triton X-100, the drug produced a well defined 4-electron polarographic wave followed by another wave of about half the height of the first wave. The current is proportional to the concentration and permits the drug to be determined by d.c. polarography in the concentration range 5.0 × 10−5 -7.0 × 10−4 M. Results obtained by the proposed method are in excellent agreement with that provided by the USP-XX method. A rapid, sensitive and accurate polarographic method for the determination of metronidazole in the tablets which are produced locally is proposed.
TL;DR: In this paper, the electrochemical reduction mechanism of p -nitrobenzoic acid (NBA) in DMF has been investigated by cyclic voltammetry, polarography and controlled potential macroscale electrolysis.
TL;DR: In this article, the authors show that an increase of the heterogeneous rate constant, a shift of the formal potentials of the V(III)/V(II) system towards more negative values, and a decrease of the diffusion coefficients are due to the resolvation of both V (III and V (II) ions when the DMF concentration in the mixture increases, as is also evident from spectrophotometric measurements.
TL;DR: Etude de la reaction d'hydratation dans H 2 SO 4 de biacetyle, bornanedione 2,3, pentanedione 1,3 and norbornanedione 4,5 aide de la voltammetrie as mentioned in this paper.
Abstract: Etude de la reaction d'hydratation dans H 2 SO 4 de biacetyle, bornanedione-2,3, pentanedione-2,3, norbornanedione-2,3, phenyl-1 propanedione-1,3 et homoadamantanedione-4,5 a l'aide de la voltammetrie
TL;DR: In this article, the mechanisms of electroreduction of 2-, 3-, and 4-pyridinecarboxaldehydes have been studied in aqueous buffered solutions of pH between 2 and 12 by means of dc and differential pulse polarography, linear-sweep voltammetry and controlled-potential electrolysis.
TL;DR: In this paper, the pseudo-polarographic properties of Zn 2+ are described and compared with square-wave polarographic measurements and with theoretical predictions, which improves the possibility of verifying experimentally the chemical models of trace metal speciation in natural waters.
TL;DR: In this paper, a sensitive determination method of tin by differential pulse polarography (DPP) is described, where the addition of tropolone to acetate supporting electrolyte at about pH 4.7 provides a 30-fold signal enhancement, giving a sensitivity comparable to that obtained in anodic stripping voltammetry, but without the need for enrichment by pre-electrolysis.
TL;DR: In this article, the effects of adsorption on the apparent stability constants of cadmium complexes as calculated from the polarographic parameters measured by the four different techniques were evaluated by means of dc, DP, ac 1, and ac 2, polarography.
TL;DR: In this paper, explicit equations for normal pulse polarography (NPP), reverse pulse polarization (RPP), DPP and DPP for a slow chargetransfer reaction have been derived in a rigorous way.
TL;DR: In this paper, the polarographic behavior of the Sudan II azo-dye in a 60% hdyroalcoholic medium has been studied using different polarographic techniques.
TL;DR: In this article, the influence of the reactant adsorption on maxima in pulse polarograms for quasi-reversible redox reactions at a stationary, planar electrode has been analyzed theoretically.
TL;DR: In this paper, the generation of methylmercury species by reactions between inorganic mercury and methylated forms of lead and tin in seawater and other matrices is described, and the reactions were investigated by 119Sn, 199Hg and 207Pb multinuclear Fourier transform magnetic resonance spectroscopy and by differential pulse polarography and anodic stripping voltammetry.
Abstract: The generation of methylmercury species by reactions between inorganic mercury and methylated forms of lead and tin in seawater and other matrices is described. The reactions were investigated by 119Sn, 199Hg and 207Pb multinuclear Fourier transform magnetic resonance spectroscopy and by differential pulse polarography and anodic stripping voltammetry. Methylmercury chloride is shown to be produced from mixtures of inorganic mercury with methyltin or methyllead species over the 10-2-10-8 M concentration range at ambient temperatures in seawater and artificial seawater.
TL;DR: In this paper, the reduction-reoxidation of spinach and Desulfovibrio desulfuricans feroxins in the presence of poly- l -lysine was investigated.
TL;DR: In this paper, the authors investigated the electroreductions and electrooxidations of 2-, 3-, and 4-pyridinecarboxaldehyde in solutions of sodium hydroxide of concentration up to 10 M (J = 16.7).
TL;DR: In this article, the electroreduction behavior of 1, 2, 4, 1, 5, and 1, 3, 5-tricyanobenzenes in acetonitrile was investigated.
TL;DR: In this paper, the electrochemical and spectroscopic behavior of mixed valence ruthenium complexes has been studied in dimethylformamide and in water utilizing the techniques of polarography, voltammetry with a platinum electrode with periodical renewal of the diffusion layer, cyclic voltageammetry and controlled electrolysis.