Search results for "Mercury electrode"
showing 10 items of 12 documents
Electrocatalytic properties of ferrooctacarboxyphthalocyanine(II). Electrocatalytic oxygen reduction on the mercury electrode in aqueous solutions
1996
Electrocatalytic reduction of oxygen in aqueous solutions in the presence of ferrooctacarboxyphthalocyanine was investigated. The decay of catalytic properties is attributed to the phthalocyanine aggregation. The mechanism for the four-electron electrocatalytic O2-reduction in neutral and basic media involving FePc(COOH)8 is proposed. It has been found that monomers of phthalocyanine, which are able to form μ-peroxo structures, are the catalytically active forms. The adsorption of various phthalocyanine forms on the mercury electrode plays a very important role in the overall catalytic reaction.
Digestion-free determination of heavy metals (Pb, Cd, Cu) in honey using anodic stripping differential pulse voltammetry and potentiometric stripping…
1995
Experiments have been carried out to assess the potential of differential pulse voltammetry and potential stripping analysis for determining Pb, Cu and Cd directly in dissolved honey samples using a flow-through cell. With the hanging mercury drop electrode Pb alone can be determined only if the electrode is first modified in-situ with Triton X 100 to increase the separation between the Pb peak and a broad, interfering adsorption peak which overlaps the Cu peak. If the (more sensitive) thin film mercury electrode is used the interference encountered is less so also Cu and Cd can be determined. With potentiometric stripping analysis Cu and Pb can be determined using normal procedures. The de…
Substituent effect on the redox potential of substituted (aryl)(2-nitrobenzo[ b ]thiophen-3-yl)amines
2001
Abstract The electronic effect of some meta- or para-substituents on the reduction of the title compounds has been investigated. The reversible reduction potential values of these compounds have been evaluated by cyclic voltammetry at a mercury electrode in 0.1 M tetraethylammoniumtetrafluoroborate, dimethylsulfoxide solutions. The substituent effect depends on both its nature and its position. The reduction potential values of the derivatives studied have been correlated with the Hammett substituent constants.
Contribution to the adsorption voltammetric determination of manganese
1994
The adsorption voltammetric determination of Mn(II) with Bromopyrogallol Red (BPR) and Mordant Red 19 (MDR) has been investigated using a hanging drop mercury electrode. In NH3/NH4Cl solution, ligands and Mn(II) complexes give well separated voltammetric peaks after enrichment onto the electrode. The conditions for determining manganese by adsorption voltammetry with these reagents have been investigated in detail, as has the influence of foreign ions on the determination. The detection limits are 4·10−10 mol/L Mn for BPR and 8·10−10 mol/L Mn for MDR, respectively.
Study on the determination of trace rhenium (VII) by the adsorption differential pulse polarography
1989
The determination of trace rhenium (VII) by differential pulse polarography in the system of H2SO4-(NHsOH)2 · H2SO4-TeO2−4 is markedly improved by the addition of Nitron, which is adsorbed on the surface of mercury electrode. The limit of detection is down to 2 × 1010 M. The adsorptive peak potential is −0.80 V (vs. SCE). In the ranges of 5 × 1010—10−8, 1 × 10−5—10−7 and 1 × 10−7—10−6M, there are good linear relationships between the peak current increment and the concentration, of which the relative standard deviations are 9.5, 6.6, 1.8% respectively with the correlation coefficients of linear regression of 0.995–0.999. The results relating to this polarographic wave show that it is an ads…
Voltammetric behavior and assay of the contraceptive drug levonorgestrel in bulk, tablets, and human serum at a mercury electrode.
2004
The cyclic voltammograms of levonorgestrel (LNG) in Britton-Robinson buffers of pH 2-11 at the hanging mercury drop electrode showed a single two-electron irreversible cathodic peak over the whole pH range. This peak may be attributed to the reduction of the 3-keto-delta-4-group in the A-ring of the LNG molecule. The interfacial adsorptive character of levonorgestrel onto the surface of the hanging mercury drop electrode was identified by means of both cyclic voltammetry and chronocoulometry techniques. A simple, sensitive, and selective square-wave adsorptive cathodic stripping voltammetric procedure was developed for the quantitation of levonorgestrel. Under the optimized operational cond…
A Voltammetric Analysis of the Electrochemical Behaviour of Onium Salts at a Mercury Electrode
1980
An analysis of the cyclic voltammograms of the reduction of various onium salt at mercury, produced more detailed information concerning the nature of the reaction pathway, in terms of adsorption, amalgam formation and kinetics of electron transfer, and lead to an interpretation of the characteristic “inverted peak”. An “auto-catalytic” reaction mechanism was indicated, and in conjunction with the preparative experiments [1, 2] a full reduction scheme proposed for the sulphonium salt ([Ph2S+ CH3)]CIO−4) and the phosphonium salt ([Ph2P+ (CH3)2]Br−). Die Analyse der Cyclovoltammogramme der reduktiven Spaltung einiger Phosphonium- und Sulfoniumsaize unterrichtet uber die an der Quecksilberkath…
The pseudostationary mercury electrode
1998
Abstract A detailed study of the pseudostationary mercury electrode is presented, based on its use in LSV. Delay times ( t 1 ) as short as 20 ms can be employed; the drop area is still given by its classical expression, and minimization of the ohmic drop allows sweep rates of a few thousands of volts per second to be used. The conditions for pseudostationarity are given; the lower sweep rates utilizable are of the order of few tenths of volt per second. Reactant adsorption is considered, and zones where rehomogenization near the electrode surface is practically either 100 or 0% are defined in a plane log t 1 /log b O ( b O is the adsorption coefficient); the diffusional or surface character…
Polarographic and voltammetric methods for the determination of elements
1978
Measurements of the correlations between current, voltage and time, when microelectrodes are used, yield qualitative and quantitative information on the elemental composition of the solution investigated, if the method of measurement is properly chosen. Instrumental development today makes it possible, even at electrodes which make measurement difficult, such as the classical dropping mercury electrode, to obtain more reliable information on detection limits and number of elements detectable, by taking into account the functional interdependence of interference parameters and signal generation. Simultaneous determination of several components is possible, especially with non-linear a. c. po…
Constant-potential electrolysis: determination of diffusion coefficients of thallium by using a hanging mercury drop electrode.
1976
The technique of constant-potential electrolysis at a stationary spherical electrode (hanging mercury drop) was investigated for the determination of the diffusion coefficient of Tl(I) in sodium citrate-sodium hydroxide medium and of Tl in mercury. Current-time curves, at controlled potential, were obtained, covering periods from 1 to 25 sec after the start of the electrolysis. The influence of applied potential, time of electrolysis, convection and shielding of the electrode was studied.