Scanning tunneling microscopic investigation of surface fouling of glassy carbon surfaces due to phenol oxidation

Wang, Joseph; Martinez, Teddy; Yaniv, Daphna R.; McCormick, Larry D.

doi:10.1016/0022-0728(91)85176-p

Cited by 64 publications

(17 citation statements)

References 22 publications

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“…Again, data obtained is shown in Table 2 and the chronoamperometric fits are presented as insets to the respective Figures. Overall n-values corresponded well to the known reduction of quinones [42,43].…”

Section: Microdisk Chronoamperometry In Propylene Carbonatesupporting

confidence: 56%

Coulometry on the Voltammetric Timescale: Microdisk Potential‐Step Chronoamperometry in Aprotic Solvents Reliably Measures the Number of Electrons Transferred in an Electrode Process Simultaneously with the Diffusion Coefficients of the Electroactive Species

et al. 2007

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Microdisk, single potential-step chronoamperometry, is applied to a range of organic substrates in the aprotic solvents tetrahydrofuran, propylene carbonate, acetonitrile and the room temperature ionic liquid [C 4 dmim][N(Tf) 2 ]. Fitting of the chronoamperometric transients was achieved using the Shoup and Szabo method [3]. Accurate values for the diffusion coefficients, D, and the number of electron(s) transferred, n, in the electrode process have been simultaneously and consistently obtained. This method is shown to be generally applicable and reliable for the determination of the number of electrons transferred in faradaic processes uncomplicated by relatively slow coupled homogeneous kinetics. Since the experiment is conducted essentially on typical voltammetric timescales it can be commended as a complementary technique for classical coulometry which is only possible on much longer timescales. The chronoamperometric method is therefore likely to be of greater relevance to the interpretation of voltammetric data.

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Section: Microdisk Chronoamperometry In Propylene Carbonatesupporting

confidence: 56%

Coulometry on the Voltammetric Timescale: Microdisk Potential‐Step Chronoamperometry in Aprotic Solvents Reliably Measures the Number of Electrons Transferred in an Electrode Process Simultaneously with the Diffusion Coefficients of the Electroactive Species

et al. 2007

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“…[6] Such a technique is based on simply holding an electrode at a suitably high potential which corresponds to the electrochemical oxidation of the analyte of interest. However, it is well documented that the electrochemical oxidation of phenolic compounds results in deactivation of the electrode surface [9,13]; a passivating polymeric film is produced which decreases the sensitivity and degrades the reproducibility although this can be overcome to a certain extent by using low phenol concentrations. The electrode materials employed in electrochemical end of column detectors include noble metals [11,12] and glassy carbon Scheme 1.…”

Section: Introductionmentioning

confidence: 98%

Electroanalytical Sensing of Green Tea Anticarcinogenic Catechin Compounds: Epigallocatechin Gallate and Epigallocatechin

2006

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A novel electroanalytical methodology for the sensing of anticarcinogenic catechin compounds epigallocatechin gallate (EGCG) and epigallocatechin (EGC) is presented. The protocol is based on the electrochemical oxidation of aminophenol in aqueous solutions, where the quinoneimine oxidation product chemically reacts with the EGCG or EGC compounds resulting in consumption of quinoneimine and consequently results in a reduction in the magnitude of the quinoneimine reduction wave, which is found to provide an analytical signal from which to indirectly detect EGCG and/or EGC. The voltammetric response of 2,6-dichloro-p-aminophenol (AP) at an edge plane pyrolytic graphite electrode in a pH 10 buffer solution to additions of EGCG is examined and AP is shown to be effective for the above analytical procedure. Basal plane pyrolytic graphite electrodes are then modified with 4-amino-2,6-diphenylphenol (phenyl-AP) where it is demonstrated that determination can proceed using the immobilized phenyl-AP in the form of surface deposited microcrystals, obviating the need for dissolving the molecules within the solution phase. We demonstrate proof-of-concept that the analysis using the modified electrode provides the determination of the total amount of catechin compounds, which is examined in a green tea sample, providing an indirect sensing technique for the determination of catechins in natural extracts.

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“…The main drawback of this substrate is the deactivation of the electrode surface. This is due to the formation of a passivating polymeric film produced by the coupling of the electrogenerated phenoxy radicals [5]. Another problem in the use of phenyl phosphate in ALP-based electrochemical enzyme immunoassay is that the direct electrochemical oxidation of phenol requires large overpotential, which causes large background current and then decreases the sensitivity.…”

Section: Introductionmentioning

confidence: 99%

“…Electrochemical enzyme immunoassay has garnered interest in clinical chemistry [1][2][3][4][5][6][7][8][9][10][11] and environmental monitoring [12,13]. The combination of electrochemical detection methods with immunoassay has enabled high sensitive, specific, rapid and inexpensive assays.…”

Section: Introductionmentioning

confidence: 99%

“…The combination of electrochemical detection methods with immunoassay has enabled high sensitive, specific, rapid and inexpensive assays. Alkaline phosphatase (ALP) is frequently used as a labeling enzyme in electrochemical enzyme immunoassay [1][2][3][4][5][6][7][8][9][10][11][12][13] and many substrates have been reported as an electrochemical substrate for alkaline phosphatase. Phenyl phosphate is hydrolysed to orthophosphate and phenol, which is then oxidised at a carbon electrode surface [4].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reagentless detection of alkaline phosphatase using electrochemically grafted films of aromatic diazonium salts

Radi

Montornés

O’Sullivan

2006

Journal of Electroanalytical Chemistry

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Scanning tunneling microscopic investigation of surface fouling of glassy carbon surfaces due to phenol oxidation

Cited by 64 publications

References 22 publications

Coulometry on the Voltammetric Timescale: Microdisk Potential‐Step Chronoamperometry in Aprotic Solvents Reliably Measures the Number of Electrons Transferred in an Electrode Process Simultaneously with the Diffusion Coefficients of the Electroactive Species

Coulometry on the Voltammetric Timescale: Microdisk Potential‐Step Chronoamperometry in Aprotic Solvents Reliably Measures the Number of Electrons Transferred in an Electrode Process Simultaneously with the Diffusion Coefficients of the Electroactive Species

Electroanalytical Sensing of Green Tea Anticarcinogenic Catechin Compounds: Epigallocatechin Gallate and Epigallocatechin

Reagentless detection of alkaline phosphatase using electrochemically grafted films of aromatic diazonium salts

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