Browsing by Author "Admassie, Shimelis(PhD)"

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    Conducting Polymer Modified Electrodes for the Electrochemical Determination of Alkaloids and Pesticides
    (Addis Ababa, Ethiopia, 2013) Amare, Meareg; Admassie, Shimelis(PhD)
    4-Am ino-3 -hydroxynaphthalene sulfonic acid was electropolymerized potentiodynamically from aqueous solution at the surface of glassy carbon electrodes. Different Electrochemical and surface characterization techniques like cyclic . vo ltammetry, impedance spectroscopy, scanning electron microscopy/energy dispersive spectroscopy, atomic force microscopy, and x-ray photoelectron spectroscopy were used to characterize the deposited electro active polymer film at the surface of glassy carbon electrodes. The poly(4-Amino-3-hydroxynaphthalene sulfonic acid) modified glassy carbon electrode was further studied as electrochemical sensor for the determination of selected alkaloids (ephedrine, theophylline, and caffeine) and organophosphorus pesticides (fenitrothion and methyl parathion) from real samples using various electroanalytical methods. The polymer modified electrode showed catalytic effect towards the studied alkaloids and organophosphorus pesticides. For the investigated alkaloids and pesticides, detection limits in the range of4.7-79 x 10.8 M and 0.79-1.1 x 10-9 M, respectively were achieved. In contrast to most of the previous reports on similar alkaloids and pesticides, po ly( 4-Amino-3-hydroxynaphthalene sulfonic acid) modified glassy carbon electrode gave lower detection limits and excellent recoveries making it potentially applicable for the determination of alkaloids and pesticides in environmental samples. The electrochemical behavior of fenitrothion at an electrochemically activated glassy carbon electrode was also investigated. The current response showed linear dependence