Browsing by Author "Magesa, Felista"

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Development of ta2o5 electrochemically reduced graphene oxide nanocomposite electochemical sensor for oxytetracycline detection in Milk
(NM-AIST, 2021-07) Magesa, Felista
Various kinds of antimicrobials are being used in the veterinary sector for therapeutic and growth promotion purposes. Significant amounts of antimicrobial residues are released in the milk and exert harmful effects such as allergic reactions, carcinogenicity, mutagenicity and teratogenicity as well as disturbance of normal flora in the gastrointestinal tract. Thus, quantification of these residues is crucial. A number of conventional detection methods that are in application, which use chromatographic, immunological and spectroscopic techniques are sensitive, selective and used for confirmatory test. However, most of them are costly, time consuming, laborious and cannot provide onsite results. In addition, most of the rapid detection tests in the market are qualitative and non-confirmatory. Hence, for quick, portable, sensitive and cost effective detection of antimicrobials, novel detection tools are needed. In this study, novel tantalum pentoxide-electrochemically reduced graphene oxide nanocomposites modified glassy carbon electrode (Ta2O5-ErGO/GCE) was developed for the detection of oxytetracycline in milk. The composition, structure and morphology of GO, Ta2O5, and Ta2O5-ErGO were characterized by X-ray diffraction and scanning electron microscopy. Oxytetracycline electrochemical behavior on the bare GCE, GO/GCE, ErGO/GCE, and Ta2O5-ErGO/GCE was studied by cyclic voltammetry. The Ta2O5-ErGO/GCE showed 2 fold increased magnification of the oxytetracycline oxidation signal in comparison to GCE, GO/GCE, ErGO/GCE electrodes. Under the optimum conditions, the currents were proportional to the oxytetracycline concentration in the 0.2 to 10 μM range with 0.095 μM as low detection limit. The preparation of Ta2O5-ErGO/GCE in the current work provides an outlook for detecting ultra-trace oxytetracycline in milk.
Electrochemical Sensing Fabricated with TaO Nanoparticle-Electrochemically Reduced Graphene Oxide Nanocomposite for the Detection of Oxytetracycline.
(MDPI, 2020-01-08) Magesa, Felista; Wu, Yiyong; Dong, Shuai; Tian, Yaling; Li, Guangli; Vianney, John Mary; Buza, Joram; Liu, Jun; He, Quanguo
A novel tantalum pentoxide nanoparticle-electrochemically reduced graphene oxide nanocomposite-modified glassy carbon electrode (TaO-ErGO/GCE) was developed for the detection of oxytetracycline in milk. The composition, structure and morphology of GO, TaO, and TaO-ErGO were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Oxytetracycline electrochemical behavior on the bare GCE, GO/GCE, ErGO/GCE, and TaO-ErGO/GCE was studied by cyclic voltammetry. The voltammetric conditions (including scan rate, pH, deposition potential, and deposition time) were systematically optimized. With the spacious electrochemical active area, the TaO-ErGO/GCE showed a great magnification of the oxidation signal of oxytetracycline, while that of the other electrodes (GCE, GO/GCE, ErGO/GCE) could not reach the same level. Under the optimum conditions, the currents were proportional to the oxytetracycline concentration in the range from 0.2 to 10 μM, and a low detection limit of 0.095 μM (S/N = 3) was detectable. Moreover, the proposed TaO-ErGO/GCE performed practically with satisfactory results. The preparation of TaO-ErGO/GCE in the current work provides a minor outlook of detecting trace oxytetracycline in milk.
Graphene and graphene like 2D graphitic carbon nitride: Electrochemical detection of food colorants and toxic substances in environment
(Elsevier, 2019) Magesa, Felista; Wua, Yiyong; Yaling, Tiana; Vianney, John-Mary; Buza, Joram; He, Quanguo; Tana, Yimin
Excessive consumption of substances such as food colorants, exposure to doses of metal ions, antibiotic residues and pesticides residues above maximum tolerance limit have a detrimental effect on human health. Hence in detecting these harmful substances, the development of sensitive, selective and convenient analytical tools is an essential step. Graphene and graphene like 2D graphitic carbon nitride have shown great promise in the development of electrochemical sensors for determining the levels of these substances in different samples. In this paper, graphene and graphene like 2D graphitic carbon nitride applications on the determination of various food colorants in foods and drinks such as azo dyes (tartrazine, allura red, amaranth, carmine and sunset yellow); metal ions contaminants, antibiotic and pesticide residues in the environment are reviewed.