Flow-injection chemiluminescent determination of nitrite in water based on the formation of peroxynitrite from the reaction of nitrite and hydrogen peroxide

In the present work, a new flow-injection chemiluminescent (CL) method for the determination of nitrite has been proposed. In acidic medium, nitrite reacts with hydrogen peroxide to form peroxynitrous acid, which is an unstable compound in acidic solution and can be quenched into peroxynitrite in basic solution. During the decomposition of peroxynitrite a weak CL was observed. With the presence of ethyldimethylcetylammonium bromide (EDAB) and uranine, the CL intensity was enhanced significantly. This CL system was developed as a flow-injection method for the determination of nitrite. The CL intensity is proportional to the concentration of nitrite in the range from 1.0 x 10(-7) to 5.0 x 10(-5) M. The analytical frequency is 30 samples/h. The detection limit (S/N = 3) is 5.0 x 10(-8) M and the relative standard deviation for nine repeated measurements of 1.0 X 10(-6) M nitrite was 4.3%. The interferences of some cationic and anionic ions on the CL were studied. The anionic ions have almost no effect on the nitrite determination. After using a cation-exchange column as pre-treatment, the interferences of the cationic ions can be removed well. This method has been satisfactorily applied to determine nitrite in tap and well waters with recoveries of 94-106%. (C) 2002 Elsevier Science B.V. All rights reserved.