Chronopotentiometric Study of the Electrooxidation of Borohydride Anion in Alkaline Medium

Borohydrides present interesting options for electrochemical power generation acting either as hydrogen sources or anodic fuels for direct borohydride fuel cells and batteries. Though there have been several papers concerning electrochemical determination of relevant thermodynamic and kinetic parameters to the borohydride system, a number of its basic aspects have not been yet systematically studied. In this paper we report chronopotentiometric studies of the electrooxidation of sodium borohydride at a gold sphere electrode in 2M NaOH solutions, at temperatures ranging from 25 to 55 °C. Gold displayed a rather good BH4 - oxidation activity, and the overall oxidation process was shown to be irreversible involving a number of electrons very close to the theoretically expected value of 8. The results suggested that the rate-determining step is an irreversible, diffusion controlled, one-electron oxidation step, for which the transfer coefficients were calculated.

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The theoretical description for the electrochemical determination of 4-4´-dihydroxyazobenzene, assisted by a composite of squaraine dye with cobalt (iii) oxyhydroxide in pair with cobalt (iv) oxide

Mediterranean Journal of Chemistry ◽

10.13171/mjc10602007011465vvt ◽

2020 ◽

Vol 10 (6) ◽

pp. 619

Author(s):

Volodymyr Valentynovych Tkach ◽

Marta V. Kushnir ◽

Oleksandra V. Ahafonova ◽

Mariia P. Mytchenok ◽

Andrii V. Bocharov ◽

...

Keyword(s):

Double Electric Layer ◽

Electrochemical Determination ◽

Theoretical Description ◽

The Other ◽

System A ◽

Diffusion Controlled ◽

Squaraine Dye ◽

Efficient Diffusion ◽

Biological Liquids

<p>The theoretical description for 4-4´-dihydroxyazobenzene CoO(OH) – assisted electrochemical determination in the mushroom pulp, food, and biological liquids has been described. In this system, a squaraine dye is used as a Cobalt(III)oxyhydroxide stabilizer and electron transfer mediator. It is shown that, contrary to the large part of the systems with cobalt (III) oxyhydroxide, this system will behave more stably, providing an efficient diffusion-controlled process. On the other hand, the oscillatory and monotonic instabilities, although possible, are caused by the double electric layer influences of either chemical or electrochemical stage.</p>

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Electrochemical Determination of Lacidipine

Journal of AOAC International ◽

10.1093/jaoac/82.5.1077 ◽

1999 ◽

Vol 82 (5) ◽

pp. 1077-1082 ◽

Cited By ~ 3

Author(s):

Juan A Squella ◽

Anny E Iribarren ◽

Juan C Sturm ◽

Luis J Núñez-Vergara

Keyword(s):

High Performance ◽

Reference Electrode ◽

Differential Pulse ◽

High Performance Liquid Chromatographic ◽

Electrochemical Determination ◽

Pyridine Derivative ◽

Diffusion Controlled ◽

Liquid Chromatographic ◽

Dihydropyridine Ring

Abstract Lacidipine is an antihypertensive drug that is oxidizable at the glassy carbon electrode. The voltammetric oxidation of lacidipine in aqueous-alcoholic solutions (70 + 30) produces a well-defined voltammetric peak when subjected to a differential pulse voltammetric experiment. This peak is due to oxidation of the dihydropyridine ring to a pyridine derivative. This voltammetric response result is irreversible, pH dependent, and diffusion controlled. The best resolution for the peak was obtained at pH 6 in Britton-Robinson buffer-ethanol (70 + 30). The peak potential at pH 6 was 800 mV against an Ag-AgCI reference electrode. A linear relationship between peak current and lacidipine concentration was obtained. For analytical purposes, a calibration curve for lacidipine that covered concentrations between 5 x 10-6 and 2 x 10-6 was used. Detection and quantitation limits were 3.52 x 10-6 and 3.78 x 10-6M, respectively. The repeatability of the measurement was 2%. On the basis of the voltammetric response, we also developed high-performance liquid chromatographic methods with electrochemical detection. For comparative purposes, we also developed a spectrophotometric method.

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