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  • 1
    Electronic Resource
    Electronic Resource
    Variation in PED response at a gold microelectrode as a function of waveform parameters when applied to alditols and carbohydrates separated by capillary electrophoresis (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 1015-1019 
    Details
    ISSN: 1040-0397
    Keywords: Capillary electrophoresis ; Pulsed electrochemical detection ; Alditols ; Carbohydrates ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Results are presented from a systematic study of the noise (N) and peak-to-noise ratio (P/N) obtained for pulsed electrochemical detection (PED) at a gold micro-wire electrode applied to a mixture of alditols and monosaccharides separated by capillary electrophoresis (CE). The electrode potentials and time periods for oxidative cleaning and reductive reactivation of the electrode were held constant in the PED waveform at minimum allowable values and the time period for digital integration of electrode current (tint) was varied from 50 to 800 ms by 50-ms intervals. The value of N was virtually independent of tint and P/N increased approximately as a linear function of tint in the range 50-200 ms corresponding to waveform frequencies in the range 4.5-2.7 Hz. A detection limit of 9 fmol glucose was determined for a 4-nL injection using tint = 200 ms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140071104
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A study of ethylamine at a gold rotating ring-disk electrode using pulsed electrochemical detection at the ring (1996)
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 726-731 
    Details
    ISSN: 1040-0397
    Keywords: Ethylamine ; Gold ; Voltammetry ; Adsorption ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Linear scan (cyclic) voltammetry at the disk with simultaneous pulsed electrochemical detection (PED) at the ring of a rotated ring-disk electrode (RRDE) is demonstrated to be applicable for studies of the complex anodic behavior of ethylamine at gold electrodes in 0.10 M NaOH. The oxidation of ethylamine at the disk occurs during positive scans concomitantly with formation of surface oxide (Au → AuOH → AuO). However, the final oxide-covered surface (AuO) is inert for further ethylamine oxidation. Data obtained at the RRDE demonstrate that the total ethylamine signal at the disk is composed of simultaneous contributions from: oxidative desorption of ethylamine preadsorbed at the oxide-free Au surface and oxidation of ethylamine transported to the disk simultaneously with oxide formation. Based on ring-disk data, preadsorbed ethylamine is estimated to correspond to a fractional surface coverage of 0.7 ± 0.1 monolayer for 10 to 60 μM ethylamine. Of this coverage, ca. 75% corresponds to ethylamine coadsorbed reversibly with OH- and 25% to ethylamine adsorbed irreversibly by a mechanism concluded to be chemisorption.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140080805
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Fast-pulsed electrochemical detection at noble metal electrodes: The frequency-dependent response at gold electrodes for chromatographically separated carbohydrates (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 269-273 
    Details
    ISSN: 1040-0397
    Keywords: Pulsed electrochemical detection ; Carbohydrates ; Liquid chromatography ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Waveforms used in pulsed electrochemical detection (PED) have frequencies of ca. 1 Hz when optimized to give a maximum signal-to-noise ratio (S/N) for carbohydrates. However, higher frequencies are desired for application of PED to capillary electrophoresis (CE) and microcolumn lipuid chromatography (MLC), which can produce narrow elution peaks. Minimization of the time periods for oxidative cleaning and reductive reactivation in PED waveforms generated by the Dionex pulsed Electrochemical Detector allows the increase in waveform frequency to ca. 3 Hz without change in the traditional time period of 200 ms, prescribed for integration of the anodic current. However, further increase in frequency requires a decrease in the integration period with a corresponding loss of signal strength.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060402
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Activation of titanium electrodes for voltammetric detection of oxygen and hydrogen peroxide in alkaline media (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 273-278 
    Details
    ISSN: 1040-0397
    Keywords: Titanium ; Voltammetry ; Oxygen ; Hydrogen peroxide ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bright, freshly-polished Ti electrodes give minimal cathodic response for O2 and H2O2 in 1.0 M NaOH. However, the response is increased gradually by repeated application of a triangular waveform within the approximate potential limits of O2 response (ca. -1.5 to -0.7 V vs. SCE). This same voltammetric pretreatment applied for excessive periods results in formation of golden films on the Ti surfaces that are active for reduction of O2 and H2O2. Levich plots of cathodic current for O2 and H2O2 at rotated golden-Ti disk electrodes in 1.0 M NaOH (-1.35 V) are linear over a large range of rotational velocity (42 to 513 rad s-1), a behavior considered to be indicative of fast heterogeneous kinetics. Ring-disk data demonstrate that a small amount of H2O2 is produced throughout the potential region for O2 reduction and H2O2 is concluded to be an intermediate product in the O2-reduction mechanism. These observations are consistent with those reported previously for single-crystal TiO2 electrodes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140090402
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Pulsed electrochemical detection at noble metal electrodes in liquid chromatography (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 367-380 
    Details
    ISSN: 1040-0397
    Keywords: Pulsed electrochemical detection ; aliphatic compounds ; liquid chromatography ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct electrochemical detection of numerous polar aliphatic compounds is achieved at Au and Pt electrodes under the control of multistep potential-time waveforms. In this technique, called “Pulsed Electrochemical Detection (PED),” the waveforms manage the sequential processes of sampling the faradaic signal, from the oxidation of analyte, followed by oxidative cleaning and reductive reactivation of the electrode surfaces. The response mechanisms in PED are strongly influenced by surface properties of the electrodes and, therefore, members of each chemical classification detected are observed to produce virtually identical voltammetric response. Consequently, applications of PED have their greatest analytical significance when coupled with Liquid Chromatography (LC) to achieve a priori resolution of complex mixtures. The basic concepts of PED are reviewed and LC-PED results are presented for a variety of samples containing mixtures of alcohols, carbohydrates, alkanolamines, amines, and sulfur compounds.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040404
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    Paper (German National Licenses)
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