Bioelectronic sniffer with a diaphragm flow-cell for acetaldehyde vapor

A bioelectronic sniffer (bio-sniffer) for gaseous acetaldehyde was constructed by incorporating an aldehyde dehydrogenase immobilized electrode (calibration range to acetaldehyde solution: 0.01-1.0 mmol/l) into a reaction cell with both gas- and liquid-phase compartments, separated by a porous diaphragm membrane. The bio-sniffer devices with two types of the diaphragm (pore size: 1-2 and 20-30 mum) were used to measure gaseous acetaldehyde from 0.525 to 20.0 and 0.105 to 5.25 ppm, respectively, with good gas-selectivity being attributed to enzyme specificity. The buffer circulation into the liquid compartment was effective for removing acetaldehyde diffusing from the gas compartment, thus permitting the continuous monitoring of acetaldehyde in the gas phase. The characteristics of the sniffer such as the calibration range and the response time can be adjusted by selecting the porous diaphragm for purpose of use. (C) 2003 Elsevier B.V. All rights reserved.