Electrochemical oxidation of 2-mercaptopyridine N-oxide on mercury electrodes in aqueous solutions

Pardo, I.; Angulo, M.; Galvín, Rafael Marín; Mellado, José Miguel Rodríguez

doi:10.1016/0013-4686(95)00249-e

Cited by 14 publications

(19 citation statements)

References 28 publications

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“…In the case of the mercury electrode, the voltammograms showed a couple of reversible oxidation-reduction peaks accompanied by a (reversible) prepeak system appearing at potentials very close to those corresponding to the main peaks, as was previously described [8,9]. For the PFCE and GCE, single irreversible one-electron voltammograms were obtained, with a reversible prepeak system appearing at potentials much more negative than the main peaks.…”

Section: Resultsmentioning

confidence: 98%

“…In addition, the diffusion coefficient of PySH, D, in our experimental conditions at pH 7.0 was calculated from the convoluted voltammograms recorded on the mercury electrode at low scan rates. Under such conditions the voltammograms corresponded to a reversible process [8]. The value of D can be easily obtained from the limiting value of the convoluted current J L…”

Section: Resultsmentioning

confidence: 99%

“…At pH > 4.5 the E 1/2 appeared pHindependent, having mean values of 486 Ϯ 7 mV and 540 Ϯ 7 mV for the GCE and the PFCE, respectively. In this pH range, only the electron transfer from the dissociated PySH must be taken into account, E 0 being -274 Ϯ 5 mV [8] (versus the same reference electrode). From these values, and by applying the Equation 4, the following values for k 0 f can be obtained:…”

Section: Resultsmentioning

confidence: 99%

“…As in previous works [6][7][8][9] precautions were taken to avoid light exposure during the experiments and also during the storage of the stock solutions of PySH.…”

Section: Methodsmentioning

confidence: 99%

“…In previous articles [8,9] the oxidation mechanism of PySH on mercury electrodes was studied and it was found that the anionic form PyS -was oxidized to the radical PyS…”

Section: Introductionmentioning

confidence: 99%

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Electrooxidation of 2-Mercaptopyridine-N-oxide (Pyrithione) at Carbon Electrodes versus Mercury Electrodes

1998

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The electrooxidation of the bactericide and fungicide agent 2-mercaptopyridine-N-oxide (PySH), or pyrithione, was investigated by using mercury (Hg), glassy carbon (GCE), plastic formed carbon (PFCE) and paste (CPE) electrodes. From controlled-potential electrolyses or chronoamperometric measurements, the number of electrons involved in the oxidation processes was found to be close to unity in all cases. Voltammetric measurements showed that the irreversibility of the electron transfer must be related to the roughness and ordering in the surface of the electrode material: as the amorphous character of the carbon electrode was increased, the transfer appeared faster. Other effects as the O/C ratio or the removal of impurities can also influence the reversibility of the transfer. The rate constants of the electron transfers at zero potential were obtained. In addition, the extension of the adsorptive oxidation decreased when the amorphous character of the electrode was increased, but the Gibbs free enthalpy of this process did not vary from one electrode to another nor for the Hg electrode.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…As in previous works [6][7][8][9] precautions were taken to avoid light exposure during the experiments and also during the storage of the stock solutions of PySH.…”

Section: Methodsmentioning

confidence: 99%

“…In previous articles [8,9] the oxidation mechanism of PySH on mercury electrodes was studied and it was found that the anionic form PyS -was oxidized to the radical PyS…”

Section: Introductionmentioning

confidence: 99%

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Electrooxidation of 2-Mercaptopyridine-N-oxide (Pyrithione) at Carbon Electrodes versus Mercury Electrodes

1998

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Determination of Zinc Pyrithione in Hair Care Products on Metal Oxides Modified Carbon Electrodes

Wang

2000

Electroanalysis

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A simple electroanalytical method for the determination of zinc pyrithione (ZPT) in commercial cosmetic products has been developed using a metal oxide modi®ed carbon paste electrode. Ingredients in the cosmetic products did not show any interference in the determination of zinc pyrithione. The electrocatalytic behavior in relation to the properties of metal oxides and the mechanism of the oxidation process was investigated using cyclic voltammetry, linear sweep voltammetry , chronoamperometry. and differential pulse voltammetry. Comparison with results obtained from high performance liquid chromatography shows good agreement. The zinc and sodium pyrithiones (Omadine) are broad±spec-tum antimicrobial agents, effective against both bacteria and fungi [1]. They were used as cosmetic preservatives in the late 1960's and the Procter and Gamble Co. discovered the antidandruff properties of zinc pyrithione (zinc 2-pyridinethiol-Noxide or ZPT). ZPT has been established as one of the most effective antidandruff ingredients for use in shampoo, conditioner, rinse and hairdressing formulations through various clinical studies [2]. In 1981 the Food and Drug Administration (FDA) reported that 29 formulations registered with the agency contained ZPT and 7 contained the sodium salt [3]. The Economic Community (EEC) Council Directive allows ZPT to be used in cosmetic products as a preservative in shampoos and conditioners as a antidandruff agent at a maximum concentration of 0.5 % and 1.0 %, respectively [4]. The toxicity of pyrithione salts by various routes of exposure has been studied extensively in several species of animals and has been described previously [5±16].Several analytical methods for pyrithiones have appeared in the literature [17±30]. In general, they involve titration with Ti(III) ion [17], thin-layer chromatography [4, 18±19], highperformance liquid chromatography [20±26] and polarography [27±30] procedures. Titrimetric methods suffer from a lack of selectivity for pyrthione and interferences in hair care products. Quantitative TLC analysis requires the use of a spectrodensitometry and ZPT decomposes in sunlight on TLC plates. Sodium pyrithione is dif®cult to quantitate by means of TLC because it reacts with metals in the TLC plate. The normal-phase HPLC conditions in the on-line Cu(II) complex formation technique can damage the analytical column in time. The direct reverse-phase HPLC analysis of ZPT is dif®cult owing to the interaction with the reverse-phase packing materials or stainlesssteel compounds of the liquid chromatography even if Zn(II) is added to the mobile phase.Although polarography offers greater speci®city it is limited to the determination of 2-pyridinethiol and 2-pyridinethiol-N-oxide. ZPT is substantially insoluble in water and is present in aqueousbased products as a dispersion of ®ne solid particles. However, ZPT is soluble in 1 M hydrochloric acid or alkaline solution. ZPT dissolved in 1 M hydrochloric acid showed a degradation of 10 % immediately, 25 % after 24 hours and 93 % af...

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Electrochemistry of Mercury

Orlik

Galus

2006

Encyclopedia of Electrochemistry

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The sections in this article are Double‐layer Properties of Hg /Water Interface Potential of Zero Charge Surface Charge Density and Capacitive Current Experimental and Theoretical Studies of the Hg /Water Interface Double‐layer Properties of Hg /Nonaqueous Media Interface Adsorption and Electrode Reactions at Hg Surface Deposition and Underpotential Deposition of Hg on Various Electrodes Underpotential Deposition of Mercury on Gold Electrodes Film Electrodes and Related Hg Electrodes Adsorption and Electrode Reactions of Inorganic Ions and Coordination Compounds of Metal Ions Analytical Applications Adsorption and Electrode Reactions Involving Organic Compounds Organic Compounds Containing Sulfur, Selenium, and Tellurium Organic Nitrogen Compounds Indicators and Dyes Vitamins and Antibiotics Enzymes and Coenzymes Other Organic Compounds Analytical Aspects of Adsorption of Organic Compounds Ammonium and Quaternary‐substituted Ammonium Amalgams

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Electrochemical oxidation of 2-mercaptopyridine N-oxide on mercury electrodes in aqueous solutions

Cited by 14 publications

References 28 publications

Electrooxidation of 2-Mercaptopyridine-N-oxide (Pyrithione) at Carbon Electrodes versus Mercury Electrodes

Electrooxidation of 2-Mercaptopyridine-N-oxide (Pyrithione) at Carbon Electrodes versus Mercury Electrodes

Determination of Zinc Pyrithione in Hair Care Products on Metal Oxides Modified Carbon Electrodes

Electrochemistry of Mercury

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