Determination of nitrite in water samples by sequential injection analysis with chemiluminescence detection on chip flow cell

A sequential injection chemiluminescence's system using a chip flow cell was described for the determination of trace amount of nitrite in water samples. Nitride reacted with hydrogen peroxide to form peroxynitrous acid in sulfuric acid medium, which was an unstable in acid medium and subsequently was quenched into peroxynitrite in basic solution. During the composition of peroxynitrite the chemiluminescence intensity was enhanced with the presence of uranin and ethyldimethylcetylammonium bromide. The reaction coil (flow cell) and holding coil was combined for tracking the emission signal. The experimental parameters including physical and chemical parameter were optimized. The interference of cations in water samples was eliminated by passing previously the sample solution trough a cation-exchange column. The linear range of the calibration graph was obtained from 1 X 10(-6) to 1 X 10(-4) mol.L-1 with a correlation coefficient of 0.999 8. The detection limit at 95% confidence was 6.8 X 10(-7) mol.L-1. The relative standard deviation at 1 X 10(-5) mol.L-1 nitrite level was 2.7 %, and the recovery of 90 %-99 % and the sampling frequency of 80 h(-1) were obtained.