Electrochemical Behaviors and Sensitive Determination of Guanosine-5’-monophosphate on Ionic Liquid Modified Carbon Paste Electrode

A new electrochemical sensor was fabricated by using ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate (OMIMPF6) modified carbon paste electrode (denoted as IL-CPE). The electrode was characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Due to the presence of high conductive IL in the carbon paste electrode, IL-CPE exhibited excellent electrocatalytic ability to the oxidation of guanosine-5’-monophosphate (GMP) with the increase of the oxidation peak current. A single well-defined irreversible oxidation peak appeared at +1.14 V in a B-R buffer of pH = 5.0 with adsorption-controlled process. The electrochemical reaction parameters of GMP oxidation were calculated with the electron transfer coefficient (α) as 0.32, the apparent heterogeneous electron transfer rate constant, ks = 9.14 × 10 s and the surface coverage, ГT = 2.34 × 10 mol cm. Under the selected conditions the oxidation peak current was proportional to GMP concentration over the range from 1.0 to 1000.0 μmol dm with the detection limit as 0.16 μmol dm (3σ) by differential pulse voltammetry. The proposed method was further applied to determine the GMP contents in artificial samples and chicken powder samples with satisfactory results. (doi: 10.5562/cca1976)