Flow-injection chemiluminescence determination of ultra low concentrations of nitrite in water

A new flow chemiluminescence method for the determination of ultra low concentrations of nitrite in water is presented. Nitrite reacts with H2O2 in acid medium to form peroxynitrous acid that is subsequently detected as peroxynitrite by the chemiluminescence reaction with alkaline solution of luminol. The detection limit of nitrite is 1 × 10−9 mol 1−1 (for 50 μl samples) and the calibration graph is linear up to 1 × 10−5 M NO−2 The relative standard deviations for 1 × 10−6 M and 3 × 10−8 M NO-2 are 1.8% and 5.4%, respectively. The interferences of cations are eliminated by passing the sample through a cation-exchange column. Common anions do not interfere. Analysis time is 3 minutes. The results are in good agreement with a standard spectrophotometric method.