Spectrofluorimetric determination of nitric oxide at trace levels with 5,6-diamino-1,3-naphthalene disulfonic acid

Based on the selective reaction that 5,6-diamino-1,3-naphthalene disulfonic acid (DANDS) traps nitric oxide (NO) in the presence of dioxygen to yield the highly fluorescent form, 1-[H]-naphthotriazole-6,8-disulfonic acid in moderately alkaline medium, a new spectrofluorimetric method for the determination of NO has been reported. The method offered the advantage of specificity, sensitivity and a simple protocol for the direct detection of NO in aqueous solution. The linear calibration range for NO was 0.04–1.44 μmol l−1 with a 3σ detection limit of 0.6 nmol l−1. The proposed method has been used to monitor the release of NO from S-nitrosocysteine, a NO-releasing agent.