ZINC-OXIDE-BASED SEMICONDUCTOR SENSORS FOR DETECTING ACETONE AND CAPRONALDEHYDE IN THE VAPOR OF CONSOMME SOUP

ZnO-based gas sensors have been exploited for the selective detection of acetone and capronaldehyde in the vapour of consomme soup. The sens itivity to acetone is much improved by the addition (5 wt.%) of two ac idic oxides, MoO3 and WO3, the highest sensitivity being attained at 5 00 and 550 degrees C, respectively. These sensors show fairly good sel ectivity to acetone over other important flavour components, methylpyr azine, dimethyldisulfide and capronaldehyde. The promoting effects are suggested to result from changes in rate and path of the catalytic ox idation of acetone. For the detection of capronaldehyde, Gd2O3- and Er 2O3-ZnO are found to show excellent sensitivities and selectivities at 300 degrees C.