Amperometric gas sensors with detection limits in the low ppb range

Amperometric gas sensors for monitoring toxic and industrially important ga ses down to low ppb concentrations at room temperature are described. The d esign of the sensors is based on a porous electrode chemically deposited on to one side of a Nafion(R) cation exchange membrane, which acts as the sens ing electrode for the trace gas to be determined. The electrode is mounted into the cell with the sensing side in direct contact with the gas entry ch amber and the bare Nafion side in contact with an internal electrolyte solu tion. It is shown that by careful selection of the experimental conditions the sensor may be tailored to the analysis of traces of gases such as sulph ur dioxide, ethylene, ethanol, acetaldehyde and acetylene. The properties o f this cell design are discussed, and the influences of parameters such as flow rate of the gas stream and humidity on the sensing behaviour are highl ighted. (C) 1999 Elsevier Science B.V. All rights reserved.