Gas-sensitive electrode applied to the continuous measurement of atmospheric ammonia

A method for the determination of ammonia in air is described. Air is pumped directly onto the head of a gas-sensitive electrode, the cap of which contains KCl and a low concentration of NH sub 4 Cl. For calibration, cleaned air flows over the surface of an ammonia solution. The ammonia concentrations of this solution is measured continuously with a second electrode. The mean ammonia concentration in the gas phase is calculated from the ammonia loss in the solution. The detection limit for gaseous ammonia is 5 myg m high -3. Effective measures to avoid interferences are described.