[Use of 7-amino-4-methylcoumarin for the spectrophotometric determination of nitrites]

A new reagent of diazotisation, 7-amino-4-methylcoumarin (coumarin 120) is proposed for the spectrophotometric determination of small amounts of nitrite. To obtain molecules with an high absorptivity, the copulation with different aromatic amines is studied. N, N-dimethylaniline leads to the best results, particularly the reproducibility. Under the optimised conditions, a good linearity (between 10 micrograms/l and 200 micrograms/l) and a good reproducibility (2-3%) according to the amount of detected nitrites are obtained.