Isopotential points in square-wave voltammetry of reversible electrode reactions

2009 ◽  
Vol 74 (10) ◽  
pp. 1489-1501 ◽  
Author(s):  
Marina Zelić ◽  
Milivoj Lovrić
Keyword(s):  
Square Wave Voltammetry ◽  
Electrode Reaction ◽  
Time Model ◽  
Model Calculations ◽  
Square Wave ◽  
Electrode Reactions ◽  
Wave Voltammetry ◽  
Electron Transfer Processes ◽  
Diagnostic Criterion ◽  
First Time

Isopotential points in square-wave voltammetry are described for the first time. Model calculations and real measurements (performed with UO22+ and Eu3+ in perchlorate and bromide solutions, respectively) indicate that such an intersection could be observed when backward components of the net response, resulting from an increase in frequency or reactant concentration, are presented together. The electrode reaction should be fully reversible because quasireversible or slower electron transfer processes give the isopoints only at increasing reactant concentrations but not at increasing square-wave frequencies. The effect could be used as an additional diagnostic criterion for recognition of reversible electrode reactions where products remain dissolved in the electrolyte solution.

Single drop square wave polarography

1981 ◽  
Vol 59 (24) ◽  
pp. 3326-3333 ◽  
Author(s):  
Louis Ramaley ◽  
Wee Tee Tan
Keyword(s):  
Square Wave Voltammetry ◽  
Signal To Noise Ratio ◽  
Single Drop ◽  
Plane Model ◽  
Square Wave ◽  
Electrode Reactions ◽  
Wave Voltammetry ◽  
Average Current ◽  
The Times ◽  
Good Agreement

The theory of square wave voltammetry for reversible electrode reactions is expanded to include average currents and currents flowing to a growing drop (single drop square wave polarography) using an expanding plane model. Excellent agreement between theory and experiment was found for the reduction of Fe(III), good agreement for the reduction of Cd(II). The expanding plane model proved superior, but not greatly superior to the simpler theory. For the case of average current the effect on the polarogram of the times at which integration is started and stopped is discussed. Integration decreases sensitivity but increases signal-to-noise ratio. The conditions for maximum analytical usefulness are presented.

scholarly journals RECENT ADVANCES AND PROSPECTS OF SQUARE-WAVE VOLTAMMETRY

2018 ◽  
Vol 39 (2) ◽  
pp. 103 ◽  
Author(s):  
Valentin Mirčeski ◽  
Leon Stojanov ◽  
Sławomira Skrzypek
Keyword(s):  
Kinetic Analysis ◽  
Square Wave Voltammetry ◽  
Square Wave ◽  
New Methods ◽  
Wave Voltammetry ◽  
Analytical Studies ◽  
Recent Advances ◽  
Voltammetric Techniques ◽  
Scan Rate ◽  
First Time

This review concerns recent methodological advances of square-wave voltammetry as one of the most sophisticatedmembers of the pulse voltammetric techniques. Besides addressing recent theoretical works and representatives ofadvanced analytical studies, an emphasis is given to a few novel methodological concepts such as kinetic analysis atconstant scan rate, cyclic square-wave voltammetry, multisampling square-wave voltammetry, and electrochemical faradaicspectroscopy. For the purpose of improving analytical performances of the technique two new methods are proposedfor the first time.

scholarly journals Probing of the pH-Dependent Redox Mechanism of a Biologically Active Compound, 5,8-Dihydroxynaphthalene-1,4-dione

2014 ◽  
Vol 67 (2) ◽  
pp. 206 ◽  
Author(s):  
Shamsa Munir ◽  
Afzal Shah ◽  
Usman Ali Rana ◽  
Imran Shakir ◽  
Zia-ur-Rehman ◽  
...  
Keyword(s):  
Square Wave Voltammetry ◽  
Reduction Process ◽  
Electrode Reaction ◽  
Biologically Active ◽  
Hydroxyl Group ◽  
General Mechanism ◽  
Semiquinone Radical ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Ph Dependent

The redox behaviour of a potential anticancer organic compound, 5,8-dihydroxynaphthalene-1,4-dione (DND), was investigated in 1 : 1 buffered aqueous ethanol using cyclic, differential pulse, and square wave voltammetry. The redox processes were found to occur in a pH-dependent diffusion-controlled manner. Presence of an α-hydroxyl group stabilised semiquinone radical of DND, formed by the gain of 1 e– and 1 H+, prevented the second step reduction, which is in contrast to the general mechanism previously reported for quinines in protic and aprotic media. In addition, our results supported an independent oxidation and reduction process. Square wave voltammetry provided evidence about the reversible and quasi-reversible nature of oxidation and reduction peaks. Based on the voltammetric results, the electrode reaction mechanism of DND was proposed. Parameters including pKa, transfer coefficient, diffusion coefficient, and electron transfer rate constant were evaluated. The values of pKa obtained from cyclic voltammetry and ultraviolet-visible spectroscopy not only agreed with each other, but also with reported values of structurally related compounds evaluated by other techniques.

scholarly journals Characterizing electrode reactions by multisampling the current in square-wave voltammetry

2016 ◽  
Vol 213 ◽  
pp. 520-528 ◽  
Author(s):  
Valentin Mirceski ◽  
Dariusz Guziejewski ◽  
Monika Bozem ◽  
Ivan Bogeski
Keyword(s):  
Square Wave Voltammetry ◽  
Square Wave ◽  
Electrode Reactions ◽  
Wave Voltammetry

scholarly journals Theory of reverse scan square-wave voltammetry influenced by the kinetics of reactant adsorption

2010 ◽  
Vol 8 (3) ◽  
pp. 513-518 ◽  
Author(s):  
Milivoj Lovrić ◽  
Šebojka Komorsky-Lovrić
Keyword(s):  
Rate Constant ◽  
Square Wave Voltammetry ◽  
Electrode Reaction ◽  
Peak Current ◽  
Kinetics Of Adsorption ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Reverse Scan ◽  
The Relationship ◽  
Kinetics Of

AbstractA model of electrode reaction complicated by slow adsorption of the reactant is developed for square-wave voltammetry with inverse scan direction. The relationship between the dimensionless net peak current and the logarithm of dimensionless rate constant of adsorption is a curve with a minimum and a maximum. For this reason the ratio of real net peak current and the square-root of frequency is a non-linear function of the logarithm of frequency and exhibits either a maximum or a minimum. The frequency of extreme serves for the estimation of the rate constant: log(k ads /D 1/2 ) = log(k*ads )crit + 0.5 log f crit , where (k*ads )crit is a critical dimensionless rate constant of adsorption. Square-wave voltammetry is sensitive to the kinetics of adsorption if k ads 2 cm s−1

scholarly journals Simulation of square wave voltammetry of three electrode reactions coupled by two reversible chemical reactions

2017 ◽  
Vol 7 (3) ◽  
pp. 119
Author(s):  
Milivoj Lovrić
Keyword(s):  
Thermodynamic Parameters ◽  
Chemical Reactions ◽  
Square Wave Voltammetry ◽  
Equilibrium Constants ◽  
Square Wave ◽  
Electrode Reactions ◽  
Wave Voltammetry

<p style="margin: 0cm 0cm 8pt; line-height: 150%;"><span lang="EN-GB">Three fast and reversible electrode reactions that are connected by two reversible chemical reactions that are permanently in the equilibrium are analysed theoretically for square wave voltammetry. The dependence of peak potentials on the dimensionless equilibrium constants of chemical reactions is calculated. The influence of the basic thermodynamic parameters on the square wave voltammetric responses is analysed.</span></p>

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