Adriano B. Oliveira

University of Bonn, Bonn, North Rhine-Westphalia, Germany

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Publications (2)2.95 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: The present work describes the substantial electrocatalytic activity of (NC)2C6H3-NHOH/(NC)2C6H3-NO redox couple-modified electrode toward the low voltage detection of l-glutathione (GSH), in neutral medium, at an applied potential of 0.4V versus Ag/AgCl. After optimizing the operational conditions, the sensor provided a linear response range for GSH from 8.0 up to 83.0 micromol L(-1) with sensitivity, detection and quantification limits of 54nA L micromol(-1), 2.7 micromol L(-1) and 8.0 micromol L(-1), respectively. The proposed sensor presented higher sensitivity when compared to other modified electrodes described in the literature and showed a stable response for at least 100 successive determinations. The repeatability of the measurements with the same sensor and different sensors, evaluated in terms of relative standard deviation, were 4.1 and 5.0%, respectively, for n=10. The developed sensor was applied for GSH determination in yeast extract and the results were statistically the same with those obtained by the comparative method described in the literature at a confidence level of 95%.
    Journal of Pharmaceutical and Biomedical Analysis 09/2008; 47(4-5):758-64. · 2.95 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: The present work describes the development of a highly sensitive amperometric sensor based on a simple and efficient carbon paste electrode modified with a new redox “mediator”, 4-nitrophthalonitrile, toward detection of cysteine (CySH) in neutral medium at an applied potential of 0.33 V vs. Ag/AgCl. The sensor showed its best performance in 0.1 mol L−1 phosphate buffer solution, at pH 7.0. After optimizing the operational conditions, the sensor provided a linear response range for CySH from 0.8 up to 13.2 μmol L−1 with sensitivity, detection and quantification limits of 37 nA L μmol−1, 0.25 μmol L−1 and 0.80 μmol L−1, respectively. The sensitivity of the proposed sensor was much higher when compared to other sensors described in the literature and showed a stable response for at least 80 successive determinations. The repeatability of the measurements with the sensor and the preparation of a series of electrodes, evaluated in terms of relative standard deviation, were 4.1 and 5.0%, respectively, for n = 10. The developed sensor was applied for cysteine determination in food supplement samples and the results were statistically the same with those obtained by the comparative method described in the literature at a confidence level of 95%.
    Journal of Electroanalytical Chemistry. 01/2008;