An ultrasensitive post chemiluminescence reaction of ammonium in NBS–dichlorofluorescein system and its application

A strong post chemiluminescence (PCL) phenomenon was observed when ammonium was injected into the reaction mixture after the finish of CL reaction of N-bromosuccinimide (NBS) and dichlorofluorescein. Based on this, a sensitive flow injection PCL method was established for the determination of ammonium. The possible CL mechanism of the reaction was proposed based on a series of experiments. The PCL intensity responded linearly to the concentration of ammonium in the range 3.0 × 10−11–1.0 × 10−7 g mL−1 with a detection limit of 1 × 10−11 g mL−1. The relative standard deviation (R.S.D.) was 1.4% for 1.0 × 10−9 g mL−1 ammonium (n = 11). This method had been applied to the determination of ammonium in samples of mineral water, tap water and river water.