Improvement of the Selectivity of Amperometric Biosensors by using a Permselective Electropolymerized Film

Dichlorophenolindophenol (DCPIP) was electrochemically deposited onto the surface of glassy carbon and platinum electrodes to form a permselective film. Cyclic voltammetry of the DCPIP coated electrode exhibited a reversible oxidation/reduction current at + 0.14 V, behavior similar to monomelic DCPIP. However, such an electrode did not mediate glucose oxidase in the presence of ß-D-glucose. For operation at + 0.7 V vs Ag/AgCl, the DCPIP electrodeposited film behaved like a permselective membrane and virtually eliminated oxidative interference currents resulting from 0.2 mM acetaminophen, uric acid and glutathione. For ascorbic acid, interfering current due to 0.2 mM ascorbate was decreased by 80%. Improvement of the selectivity due to ascorbic acid was achieved using an electrodeposited film prepared from a mixture of DCPIP with diaminobenzene or resorcinol.