A simple and quick FIA spectrophotometric procedure is proposed for nitrite determination. The method is based on the reaction of nitrite ion with the non-cancerous reagent, 3,6-diamino acridine. The acridine aqueous solutions are stable for long time periods. The method shows competitive precision and selectivity and a wider linear range than many other FIA procedures. The method can also be applied to determination of the nitrate by adding a suitable reductive copperized cadmium column to the proposed FIA manifold.