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

摘要

A new electrochemical sensor was fabricated by using ionic liquid (IL) 1-octyl-3-methylimid-azolium hexafluorophosphate (OM1MPF_6) 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 (a) as 0.32, the apparent heterogeneous electron transfer rate constant, k_s = 9.14 × 10~(-5) s~(-1) and the surface coverage, Γ_T = 2.34 × 10~(-9) mol cm~(-2). Under the selected conditions the oxidation peak current was proportional to GMP concentration over the range from 1.0 to 1000.0 umol dm~(-3) with the detection limit as 0.16 umol dm~(-3) (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.