Investigations into the use of gas-sensing membrane electrodes for the determination of carbon dioxide in power station waters

Abstract

Gas-sensing membrane electrodes have been assessed for use in the determination of carbon dioxide in power station waters. The Radiometer, Type E5036, electrode has the most satisfactory performance, and the system is convenient and simple for the investigation of abnormal levels of carbon dioxide that arise at start-up or during the commissioning stages; the limit of detection (about 0·1 µg ml^–1) is not low enough for the routine monitoring of normal operation levels. The electrode has been used for both discrete analysis and on-line continuous monitoring. Standard deviations of 2·0, 0·3 and 0·13 µg ml^–1 were obtained at concentration levels of 23·2, 5·00 and 2·32 µg ml^–1, respectively. The response times at concentrations greater than 1 µg ml^–1 were found to be within the range 3–7 min for a 10-fold increase in concentration. Of the species expected in power stations only sulphite ion, at high concentration, caused interference.