NOVEL HEXACYANOFERRATE(III) MODIFIED GRAPHITE DISC ELECTRODES AND THEIR APPLICATION IN ENZYME ELECTRODES .1.

We report a novel procedure for the electrochemical modification of gr aphite disc electrodes with potassium hexacyanoferrate(III) using cycl ic 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 cite d for Prussian blue type films. These modified electrodes exhibited ex cellent stability during repeated potential cycling in 0.1 M potassium chloride with no difference in peak heights between the second and th irtieth scans. We used glucose oxidase as the model enzyme to investig ate application of these novel modified graphite disc electrodes in th e development of biosensors. The resulting glucose sensors exhibited a response to glucose at potentials as low as 450 mV vs. saturated calo mel 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 pero xide with sensitivity of 0.70 mu A mM(-1) cm(-2) (geometric area). The effect of ascorbic acid, 4-acetamidophenol and uric acid, common inte rferents found in blood, is also reported. (C) 1996 Published by Elsev ier Science Limited