Spectrofluorimetric determination of nitrite with 5,6-diamino-1,3-naphthalene disulfonic acid Original Research Article

A simple, sensitive and specific spectrofluorimetric method for the determination of nitrite has been developed. It is based on the selective reaction of nitrite with 5,6-diamino-1,3-naphthalene disulfonic acid (DANDS) in acidic medium to form 1-[H]-naphthotriazole-6,8-disulfonic acid, a highly fluorescent compound in alkaline medium. The linear calibration range for nitrite was 0.8–112 ng ml−1 with a 3σ detection limit of 0.09 ng ml−1, lower than those of other spectrofluorimetric methods. The proposed method has been applied to the determination of nitrite in tap water (33 ng ml−1) and lake water (17 ng ml−1) without extraction, with R.S.D. (n=6) of 1.7 and 4.9%, respectively and recoveries of 98–102%.