CONTINUOUS MONITORING OF AMBIENT AMMONIA WITH A MEMBRANE-ELECTRODE-BASED DETECTOR

A novel detection system suitable for the direct and continuous measurement of atmospheric ammonia levels in the 0. 4-260 ppbv range is described. In the proposed system, an appropriate buffer reagent flows through a narrow-bore gas-permeable 'sniffer' tube and on to a flow-through ammonium-selective membrane electrode. The ammonium activity detected by the electrode in the reagent stream is directly proportional to the gas-phase ammonia concentrations surrounding the sniffer tube. It is shown that under optimized operating conditions, the system can readily detect smaller fluctuations in room-air ammonia levels which are measured to be in the 2-10 ppbv range.