Abstract
A fluorometric flow injection analysis for nitrite in saliva has been developed. The fluorescent reagent, 4-hydroxycoumarin, was nitrosated with the injected nitrite in acidic medium, and reduced subsequently with sodium thiosulfate to give 3-amino-4-hydroxycoumarin, which was fluorescent in alkaline medium. Under the optimized conditions, the detection limit was 4.3×10-8M at a sample volume of 210μl, and the relative standard deviations(n=8) for 20 and 100ng/ml nitrite solutions were 2.8 and 1.7%, respectively. The sampling rate was 30 samples per hour. Saliva was diluted with water, and analyzed by the FIA system after centrifugation. The recovery data indicated that the present method was applicable to saliva samples.
