Novel hexacyanoferrate(III) modified graphite disc electrodes and their application in enzyme electrodes .1.

We report a novel procedure for the electrochemical modification of graphite disc electrodes with potassium hexacyanoferrate(III) using cyclic voltammetry. Cyclic voltammograms of the modified electrodes in 0.1 M potassium chloride showed two redox couples, at 0.22 and 0.148V and at 0.923 and 0.798 V. These redox potentials correspond to those cited for Prussian blue type films. These modified electrodes exhibited excellent stability during repeated potential cycling in 0.1 M potassium chloride with no difference in peak heights between the second and thirtieth scans. We used glucose oxidase as the model enzyme to investigate application of these novel modified graphite disc electrodes in the development of biosensors. The resulting glucose sensors exhibited a response to glucose at potentials as low as 450 mV vs. saturated calomel electrode with a linear range up to 1.5 mM glucose and sensitivity of 50 +/- 10 nA mM(-1) cm(-2) (geometric area). The modified graphite disc electrodes displayed an electrocatalytic effect on hydrogen peroxide with sensitivity of 0.70 mu A mM(-1) cm(-2) (geometric area). The effect of ascorbic acid, 4-acetamidophenol and uric acid, common interferents found in blood, is also reported. (C) 1996 Published by Elsevier Science Limited