Electrochemistry of 2,6-diaminopurine on multiwall carbon nanotube modified glassy carbon electrode


Abstract: The electrochemical oxidation of 2,6-diaminopurine (2,6-DAP) was studied in pH 7.4 phosphate buffer solution on multiwall carbon nanotube modified glassy carbon electrode (MWCNT/GCE) over a temperature range of 20 to 50 °C using cyclic voltammetry. 2,6-DAP oxidation on MWCNT/GCE showed a well-defined and irreversible oxidation peak at about 0.72 V vs. Ag/AgCl at pH 7.4. The oxidation potential of 2,6-DAP linearly varied with pH over the range of 3.0 to 10.0 with a slope of --0.0547 V/pH, implying that 2 protons were accompanied by 2 electrons transferred in the electrochemical reaction. The activation energy, Ea, of oxidation reaction was found to be 33.10 \pm 1.88 kJ/mol. The differential pulse voltammetric determination of 2,6-DAP was also studied. The peak currents increased linearly with increasing of the 2,6-DAP concentration range from 0.4 \mu mol/L to 80 \mu mol/L. The linear regression equation appeared as I_p/\muA = --(1.66 \pm 0.42) + (4.21 \pm 0.11) [2,6-DAP]/\mu mol/L, R^2 = 0.9982, and the detection limit (S/N = 3) was 3 \times 10^{-7} \pm 0.015 mol/L (n =3). The electrocatalytic oxidation of 2,6-DAP on MWCNT/GCE showed that acid pretreated multiwall carbon nanotube can be used in new applications in electrochemical determinations of biologically important compounds.

Keywords: Carbon nanotubes, 2,6-diaminopurine, activation energy, voltammetry

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