Redox measurements in aqueous solutions — A theoretical approach to data interpretation, based on electrode kinetics

Peiffer, Stefan; Klemm, Otto; Pecher, Klaus; Hollerung, Roland

doi:10.1016/0169-7722(92)90041-c

Cited by 56 publications

(52 citation statements)

References 18 publications

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“…Measurements of E h depend on concentrations of redox couples, but the contribution of redox couples to E h highly depends on electrode affinity, exchange density and kinetics at the surface of electrodes, in which E h measurements may be dominated by a single redox couple (Peiffer et al 1992). Although oxygen is often considered to be a dominant redox active compound in the interpretation of E h , an increased penetration depth of oxygen did not result in shifts in E h .…”

Section: Discussionmentioning

confidence: 99%

Contribution of bacteria to redox potential (E h) measurements in sediments

Hunting

Kampfraath

2012

Int. J. Environ. Sci. Technol.

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Section: Discussionmentioning

confidence: 99%

Contribution of bacteria to redox potential (E h) measurements in sediments

Hunting

Kampfraath

2012

Int. J. Environ. Sci. Technol.

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“…4,14 It is possible that the measured redox potential is governed by one species, particularly if its concentration and electron exchange rate is significantly higher than other species present in solution. 5,14 To increase the quantitative usefulness of redox potential measurements in complex environments, it's necessary to design elec- * Electrochemical Society Student Member.* * Electrochemical Society Active Member. z E-mail: mmcollinson@vcu.edu trodes that will minimize the impact of contamination on the electrode response and facilitate electron exchange with as many redox species as possible.…”

mentioning

confidence: 99%

Potentiometric Measurements in Biofouling Solutions: Comparison of Nanoporous Gold to Planar Gold

Farghaly

Lam

Freeman

et al. 2015

J. Electrochem. Soc.

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Potentiometric redox measurements were made in solutions of increasing biological complexity starting with buffer solutions containing either potassium ferri/ferrocyanide or ascorbic acid and finishing with plasma and blood. When the concentration of ferri/ferrocyanide was high (∼0.2 mM), both biofouled planar and nanoporous gold electrodes gave Nernstian slopes of 55-59 mV. However, at or below a critical concentration (≤ 0.1 mM), ∼20% loss in sensitivity was observed at planar gold in contrast to nanoporous gold where Nernstian behavior was retained. For ascorbic acid, a Nernst slope of −41 mV was observed at biofouled nanoporous gold electrodes. In contrast, biofouled planar gold electrodes failed to give any potentiometric redox response. At all concentrations studied, cyclic voltammetric measurements on biofouled electrodes revealed significant impairment of faradaic electroactivity at planar gold electrodes while no impairment was shown at nanoporous gold. These results indicate that nanoporous gold is an ideal electrode material to use when making both potentiometric and cyclic voltammetric measurements, particularly in complex solutions containing relatively low concentrations of redox molecules. As proof of concept, the redox potential of plasma and blood has been measured using nanoporous and planar gold electrodes and their values compared. Potentiometry is a technologically simple and inexpensive approach to obtain important information about the redox state of a system and/or the concentration of ions in solution.1,2 The measurement itself is simple in that all that is needed is a high impedance voltammeter, a stable reference electrode, and a suitable indicating electrode. In contrast to voltammetric measurements, no current flows, and the concentration of the redox species in solution does not change nor does the indicating electrode surface become altered as a potential is not applied. Likely the most popular potentiometric measurement is the measurement of pH using an ion-selective electrode that incorporates a thin membrane responsive to the activity of protons in solution. 3For the work described herein, the indicating electrode is an inert metallic redox electrode that is purposely designed to be nonselective and will 'ideally' respond to all redox active species in solution able to exchange electrons with the metallic surface.1,2 When the indicator electrode is immersed in solution, it will equilibrate electrochemically with the dissolved redox species and a potential will develop at its surface. The measured potential is governed by factors such as (1) the redox species present, (2) their concentrations (activities), and (3) the rate of electron exchange with the electrode.2,4,5 Such redox measurements have been used to characterize the redox state of solutions with a complex matrix including milk, cheese, sludge, water and biological systems. [6][7][8][9][10][11][12][13] An important and often neglected factor in the measurement of redox potential is the nature of the electrode surface, pa...

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“…Equilibrium in this context means that the forward and backward reaction rates of the electron transfer processes via the electrode surface tend to counterbalance each other. A detailed derivation of the electrochemical principles underlying the measurements of redox voltages is given by PEIFFER et al (1992a). The following discussion follows their theoretical treatment and the reader is referred to this article for further information.…”

Section: Measurement Of Redox Voltages At Redox Electrodesmentioning

confidence: 99%

“…Under certain conditions the electrode voltage can be controlled by one single redox couple. PEIFFER et al (1992a) performed a sensitivity analysis in order to check the influence of the parameters involved in the electrode reaction on the electrode voltage. As a rule, it can be derived that a single redox couple controls the electrode voltage, if either its standard rate constant or its concentration, or both of them, are two orders of magnitude higher than that of the other redox couples.…”

Section: Measurement Of Redox Voltages At Redox Electrodesmentioning

confidence: 99%

“…Further complications are caused by the adsorption of dissolved components, which affect the electron transfer between the electrode surface and the bulk solution (BARD & FAULKNER, 1980, see also the discussion in PEIFFER et al, 1992a). As this discussion shows, measurements of redox voltages do not provide a general parameter to quantitatively characterise the redox state of an aqueous solution.…”

Section: Measurement Of Redox Voltages At Redox Electrodesmentioning

confidence: 99%

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