Chemiluminescence flow system for the determination of ammonium ion

A novel chemiluminescence (CL) system for ammonium ion combined with flow-i njection analysis is presented in this paper. It is based on the CL reactio n between luminol, immobilized electrostatically on an anion-exchange colum n, and chlorine electrochemically generated on-line via a platinum electrod e from hydrochloric acid in a coulometric cell. Ammonium ion reacts with ch lorine and decreases the observed CL intensity. The system responds linearl y to ammonium ion concentration in the range 1.0-100 mu M, and the detectio n limit is 0.4 mu M. A complete analysis, including sampling and washing, c ould be performed in 1 min with a relative standard deviation of < 6.0%. Th e system is stable for over 500 determinations and has been applied success fully to the determination of ammonium ion in rainwater samples. (C) 1999 E lsevier Science B.V. All rights reserved.