DIRECT MONITORING OF FORMALDEHYDE VAPOR AND DETECTION OF ETHANOL VAPOR USING DEHYDROGENASE-BASED BIOSENSORS

Biosensors capable of directly detecting low levels of formaldehyde an d ethanol vapour were constructed, Both biosensors are based on dehydr ogenase enzymes which produce reduced nicotinamide adenine dinucleotid e as part of the oxidation of formaldehyde and ethanol, The enzymes we re immobilized in a reverse micelle medium which did not dehydrate sig nificantly over time, and allowed direct gas-phase monitoring, A scree n-printed electrode was used as transducer. Formaldehyde and ethanol v apour partitioned into the reverse micelle media, where it was acted u pon by the relevant enzyme, Reduced nicotinamide adenine dinucleotide was oxidized at the working electrode at a potential of 800 mV versus an Ag/AgCl reference electrode, Formaldehyde could be measured over th e concentration range 1 ppb-1.3 ppm and ethanol could be detected over the range 50-250 ppm.