Development of a disposable ethanol biosensor based on a chemically modified screen-printed electrode coated with alcohol oxidase for the analysis of beer

A disposable amperometric biosensor for the measurement of ethanol has been developed. It comprises a screen-printed carbon electrode doped with 5% cobalt phthalocyanine (CoPC-SPCE), and coated with alcohol oxidase; a permselective membrane on the surface acts as a barrier to interferents. The measurement of ethanol is based on the signal produced by H2O2, the product of the enzymatic reaction. Optimisation studies were performed using amperometry in stirred solution and the magnitude of the signal was found to be dependent on pH, enzyme loading, type of membrane and applied potential. The same technique was used to evaluate the biosensor for the determination of ethanol in samples. The results obtained compared well with the manufacturers specifications. In order to test the possibility of using the devices in the field, chronoamperometry was also used to determine ethanol in the same beer samples. The precision and recovery data again indicated that the biosensor should give reliable results under the conditions described.