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  • 1
    Electronic Resource
    Electronic Resource
    Imaging of immobilized antibody layers with scanning electrochemical microscopy (1995)
    s.l. : American Chemical Society
    Analytical chemistry 67 (1995), S. 3578-3582 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00115a030
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  • 2
    Electronic Resource
    Electronic Resource
    Capillary Enzyme Immunoassay with Electrochemical Detection for the Determination of Atrazine in Water (1995)
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 43 (1995), S. 1098-1104 
    Details
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jf00052a044
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  • 3
    Electronic Resource
    Electronic Resource
    Capillary enzyme immunoassay with electrochemical detection for determining indole-3-acetic acid in tomato embryos (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 170-174 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An amperometric immunoassay for indole-3-acetic acid (IAA) in tomato embryos was developed. The antibody against IAA was covalently bound to the chemically modified inner surface of a 22 μL silica capillary. The competitive binding of methylated IAA and an IAA alkaline phosphatase conjugate for a limited amount of antibody was accomplished in the silica capillary in 20 min. The enzymatic product p-aminophenol, produced from p-aminophenyl phosphate, was determined by flow injection analysis with amperometric detection. A detection limit for IAA of 3 pg/μL was obtained. The average concentration of IAA in mature embryos measured by this method is 0.37 ± 0.03 μg/g. Although isotope dilution GC-SIM-MS can achieve the same detection limit, the sample analysis is not feasible in such a complicated matrix and further purification and separation are required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051318
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  • 4
    Electronic Resource
    Electronic Resource
    Blocking behavior of self-assembled monolayers on gold electrodes (1997)
    Springer
    Journal of solid state electrochemistry 1 (1997), S. 148-154 
    Details
    ISSN: 1433-0768
    Keywords: Key words Self-assembled monolayers ; Thiols ; Gold ; Electrode ; Adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Self-assembled monolayers (SAMs) with metal electrodes, especially thiols on gold, are the subject of this investigation because of the unique properties of SAM-modified surfaces. Normal alkanethiols are used to modify the surface of a conventional gold electrode to block certain ions such as Pb(II) and Cu(II) from the surface of the electrode. Normal alkanethiols are also used to study the SAM-gold interfacial adsorption-desorption behavior of the self-assembled monolayer. The effects of varying chain length of SAMs, varying concentration of the alkanethiol solutions, immersion time of the pure gold electrode in the SAM solution, and the stability of a SAM-modified gold electrode in fresh chloroform are investigated using the oxidation-reduction peaks of gold. Conditions that optimize the surface coverage and the uniformity of the SAMs have been determined. Normal alkanethiols proved to be a good insulator on the electrode surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100080050039
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  • 5
    Electronic Resource
    Electronic Resource
    Stripping voltammetry of copper and lead using gold electrodes modified with self-assembled monolayers (1997)
    Springer
    Journal of solid state electrochemistry 1 (1997), S. 241-247 
    Details
    ISSN: 1433-0768
    Keywords: Key words Underpotential deposition ; Stripping analysis ; Self-assembled monolayers ; Multiple stripping peaks ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract One problem associated with using bare solid metal electrodes, such as gold and platinum, in stripping analysis to determine heavy metal ions such as lead and copper ions in dilute solutions is that underpotential deposition (UPD) gives multiple stripping peaks in the analysis of mixtures. These peaks are often overlapped and cannot be conveniently used for analytical purposes. Bifunctional alkylthiols, such as 3-mercaptopropionic acid, with an ionizable group on the other terminal end of the thiol can form self-assembled monolayers (SAMs) on the surface of the gold electrode. It is shown that such an SAM-modified gold electrode minimizes the UPD effects for the stripping analysis of lead and copper. The anodic peak potential shifts and the peak shape changes, indicating that the SAM changes the deposition and stripping steps of these heavy metal ions. Thus, the sensitivity levels for both single species and mixtures can be significantly improved for the conventional solid electrodes. The mechanism of the deposition reaction at the SAM-modified gold electrodes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100080050055
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  • 6
    Electronic Resource
    Electronic Resource
    An Analytical Study of the Redox Behavior of 1,10-Phenanthroline-5,6-dione, its Transition-Metal Complexes, and its N-Monomethylated Derivative with regard to their Efficiency as Mediators of NAD(P)+ Regeneration (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 79-88 
    Details
    ISSN: 0947-6539
    Keywords: catalysis ; cobalt ; cofactors ; redox systems ; ruthenium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis as well as the chemical and electrochemical properties of homoleptic and heteroleptic (trispyridyl-methylamine as coligand) transition-metal complexes (Ru and Co) of 1,10-phenanthroline-5,6-dione (PD) and of its N-monomethylated derivative (PDMe+) are described. In particular, their ability to abstract hydride ions was studied. Electrochemical investigations with cyclic voltammetry, rotating disk electrode experiments, and spectroelectrochemical methods at different pH values gave an insight into the complex electrochemistry of the compounds described, which is strongly influenced by a hydration pre-equilibrium. The electrochemically active quinone form of the transition-metal complexes can be reduced to the hydroquinone state in acidic solution and to their transition-metal-stabilized semi-quinone states for neutral and basic solutions, whereas PDMe+ is reduced to the hydroquinone state in both acidic and neutral solutions. The compounds can also be reduced chemically, and are efficient catalysts for the indirect oxidation of the enzymatic cofactor NAD(P)H. For the indirect aerobic NAD(P)H oxidation, up to 900 turnovers per hour can be observed, an achievement yet to be reached by other catalyst systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030114
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  • 7
    Electronic Resource
    Electronic Resource
    Electron transfer through an immunoglobulin layer via an immobilized redox mediator (1996)
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 143-146 
    Details
    ISSN: 1040-0397
    Keywords: Redox mediators ; Immunoglobulin G ; Polyvinyl ferrocene ; Butyl ferrocene ; lmmunosensor model ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a step towards a voltammetric immunoassay with antibodies directly attached onto the electrode surface, the mediated oxidation of a redox active label has been investigated with a model system. Butyl ferrocene served as a model for the mediator and was coimmobilized onto a glassy carbon electrode within a layer of bovine immunoglobulin G, which mimiked the antibody. An overlaid polyvinyl ferrocene layer was employed to simulate a ferrocene-tagged high molecular weight antigen bound to the immobilized antibodies. A mediated electron transfer could only be demonstrated with butyl ferrocene as mediator, whereas other compounds failed to support an electron transfer between the polyvinyl ferrocene layer and the electrode through the layer of immunoglobulin.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140080209
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  • 8
    Electronic Resource
    Electronic Resource
    The analysis of fountain pen inks by capillary electrophoresis with ultraviolet/visible absorbance and laser-induced fluorescence detection (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 31-41 
    Details
    ISSN: 0173-0835
    Keywords: Questioned documents ; Inks ; Capillary zone electrophoresis ; UV/VIS and LIF detection ; Separation and comparison ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Information on the identity of inks adds to the circumstantial evidence in legal cases involving fraudulent documents. In combination with optical methods, multiple thin-layer chromatography (TLC) is currently the analytical tool used by forensic chemists to separate, compare and distinguish inks based on their dye composition. In our studies, capillary electrophoresis (CE) was used for the analysis of water-soluble fountain pen inks. Inks are complex mixtures of synthetic organic and inorganic dyes, surfactants, resins and other components. The investigations included the development of an electrophoretic separation method, the optimization of an extraction procedure for inks from paper as well as the evaluation of ultraviolet/visible (UV/VIS) absorbance and laser-induced fluorescence (LIF) detection for the analysis of inks by CE. Good results for the separation of 17 blue and black inks of different manufacturers and countries of origin were obtained with 100 mM borate buffer, pH 8.0, containing 20% methanol. The electropherograms of the inks and their extracts from paper showed patterns that were in most cases distinctly different from each other. Ultraviolet/visible scans can be used to compare spectra of the separated main and trace components of inks. Fluorescence detection at different excitation and emission wavelengths was more sensitive, but added to the complexity of the electropherograms due to the excitation of coextracted fluorescing paper components. The resolution power of CE combined with the information content provided by the detection modes investigated prove CE to be a powerful tool for the identification of water-soluble inks used on paper documents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190108
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