GAS-PHASE BIOSENSOR FOR ETHANOL

A gas-phase biosensor was constructed using an immobilized alcohol oxidase (AOD) enzyme electrode and a unique reaction cell with both gas- and liquid-phase compartments separated by a diaphragm membrane. The sensor was evaluated for the measurement of gaseous ethanol with two types of porous poly(tetrafluoroethylene) diaphragm membranes (pore size 30-60 pm, thickness 0.13 mm; pore size 1-2 mu m, thickness 0.25 mm) and was used to measure ethanol in the gas phase from 0.358 to 1242 ppm, covering the sense of smell in humans and the concentration range encountered in breath after alcohol drinking. The sensor possessed high selectivity for ethanol in the presence of other gas-phase chemicals and gave a negligible response to these chemicals. The short lifetime of the device was caused by deactivation of the unstable AOD, which was consistent with previously reported results.