ELECTROCHEMICAL SENSOR FOR ACETYLENE

The fixed potential amperometric sensing of acetylene in the gas phase on a gold-Nafion electrode was found to suffer from catalytic poisoni ng effects with resultant loss of sensitivity. However, by applying a potential pulse program, the sensitivity of the electrode could be res tored. With suitable choice of applied potentials, electrochemical ads orption of acetylene took place, allowing an increase in sensitivity. For an adsorption time of 60 s, a 20-fold increase in sensitivity and a detection limit of 20 ppb were obtained. Compounds which, in a fixed potential amperometric mode, would be considerable interferants were found not to preadsorb along with acetylene. An increase in selectivit y was, therefore, also achieved.