Electrochemical Oxidation Behavior of Guanosine and Guanosine - 5'-Monophosphate at a Pencil Graphite Electrode
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| Year of publication | 2014 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Purine nucleosides are well known for their metabolic and biological effects in the human system. Their detection and determination have become increasingly important in the field of biomedical research owing to their importance in normal cellular functions. The electrochemical technique is powerful method for the detection of guanosine (Guo) and guanosine-5'-monophosphate (GMP) due to the advantages of rapid response, low cost, simple operation, time saving, high sensitivity, and excellent selectivity. In this work, the electrochemical oxidation behaviors of Guo and GMP were investigated by a pencil graphite electrode (PeGE) at pH 2.5 - 9.3 and scan rates in the range of 200 - 800 mV/s. The advantages of PeGE over the existing carbon electrodes are a high electrochemical reactivity, commercial availability, good mechanical rigidity, and low cost. It seems that pH 5.67 is the best pH for simultaneous detection of Guo and GMP; therefore this pH was selected as the optimal pH. With increasing pH, a linear shift of Epa towards a negative potential was obtained. The slopes of -54.60 and 55.50 mV/pH indicate that the numbers of protons and electrons involved int he process of electrochemical oxidation of GMP and Guo are equal. With increasing scan rate, Epa shifted positively,a linear relationships can be obtained int he range of 200-800 mV/s. According to the Laviron equation and the elimination procedure,?n was calculated to be 0.99. For two electrons the coefficient of electron transfer ? is assumed to be 0.5. Integrating voltammetric results obtained in pH and scan rate studies, the electrooxidation of Guo and GMP at the PeGE should be a two - electron and two proton process, which can be attributed to the fact that the Guo and GMP molecules are oxidized to form 8-oxoguanine, occuring in the nucleophilic - N(7)=C(8)- bond of guanine base |
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