Determination of nitrite by inhibition of the chemiluminescence of acriflavine in a flow-injection assembly

The indirect determination of nitrite was performed with a flow-injection a ssembly on the basis of the inhibition of the analytical output obtained in a luminometer by oxidation of acriflavine. The acriflavine solution merged with the nitrite and the resulting mixture was injected into a pure water stream. This solution merged with the oxidant solution (potassium permangan ate in sulfuric acid medium) and the resulting chemiluminescence was affect ed (inhibited) by the presence of nitrite after reaction with the aminoacri dine. The method was applicable over the range 10-800 mug l(-1) of nitrite with a correlation coefficient of 0.9960. The relative standard deviation w as 1.4% and the throughput was 76 samples h(-1). The influence of foreign s ubstances was also tested. A solid-phase reactor, filled with Amberlite IRA -900, was inserted in the assembly for the on-line preconcentration of nitr ite; the analytical output resulted in an increase of up to 11.5-fold. The method was applied to the determination of nitrites in residual waters. ind ustrial formulations and soil samples.