Glucose Sensor Based on Ubiquinone-Modified Carbon Paste Electrode

Two types of carbon paste electrodes containing ubiquinone (CoQ) and glucose oxidase (GOD) were constructed, and their electrochemistry and amperometric response to substrate were investigated. For one type of electrode in which the surface of carbon particles was covered with a part of CoQ molecules added, it was found that the CoQ adsorbed on the carbon particles exerted an insulating effect on the electrode reaction. For the other type of electrode in which the surface was preadsorbed with GOD and most of CoQ was dissolved in the liquid paraffin phase, it was demonstrated that CoQ served as an electron transfer mediator. The latter electrode showed amperometric responses to glucose in the applied potential range 300 - 500 mV and a linear response in the range 0.2 - 4.0 mM in an electrolyte solution (pH 7.0).