DETERMINATION OF AMMONIUM ION IN RAINWATER AND FOGWATER BY FLOW-INJECTION ANALYSIS WITH CHEMILUMINESCENCE DETECTION

Reaction between ammonia and hypobromite in alkaline solution was found to give chemiluminescence. The maximum wavelength of the chemiluminescence is similar to 710 nm. This chemiluminescence reaction has been used for the determination of ammonium ion concentration in rainwater and fogwater with a flow injection analysis system. The detection limit of ammonium ion was 6.1 x 10(-6) mol/dm(3) (3 RSD). The dominant components in rainwater such as NO3-, SO42-; and Cl-, do not interfere with the determination, but humic acid and urea do. The interference can be removed by inserting a glass filter between the chemiluminescence cell and the photomultiplier tube, because the peak wavelengths of the emission are different for both chemiluminescence species. Rainwater and fogwater samples can be rapidly determined by this method without any pretreatment. The results determined by the present method were in good agreement with-the ion chromatographic method and the indophenol spectrophotometric method.