Amperometric gas sensors with detection limits in the low ppb range Original Research Article

Amperometric gas sensors for monitoring toxic and industrially important gases down to low ppb concentrations at room temperature are described. The design of the sensors is based on a porous electrode chemically deposited onto one side of a Nafion® cation exchange membrane, which acts as the sensing 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 chamber and the bare Nafion side in contact with an internal electrolyte solution. 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 sulphur dioxide, ethylene, ethanol, acetaldehyde and acetylene. The properties of 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 highlighted.