ORGANIC PHASE BIOSENSORS

Abstract

Two types of amperometric enzyme electrode for use in organic solvents are devised. One of them incorporates horseradish peroxidase for the determination of hydrogen peroxide in organic media. The enzyme was co-adsorbed with an electron mediator, potassium ferrocyanide, on the surface of a graphite foil electrode, making reagentless measurementpossible. The electrode can be operated in dioxane, chloroform and chlorobenzene, the presence of a small quantity of aqueous buffer being essential for sensor activity. During two weeks of intermittent use the sensitivity of the electrode decreases by 60 %. At least 50 assays can be performed with a single sensor. As an alternative approach to assemble oxidase sensors for use in organic solvents, tyrosinase was adsorptively coupled to a dialysis membrane combined with a conventional oxygen probe. The sensor was successfully employed for the direct determination of phenolin chloroform.