A reversible chemosensor for nitrite based on the fluorescence quenching of a carbazole derivative

The carbazole derivative, with an amino group in 9-position (9-methylacryloylamino carbazole (MAC), has been utilized to prepare a fluorescent sensor and used for the determination of NO2− based on the reaction between nitrite (NO2−) and excess I− to form I3−, which can quench the fluorescence of carbazole derivative. MAC, as a fluorescent carrier, has a terminal double bond and is covalently immobilized on a quartz glass plate surface by photo-polymerization to prevent the leakage of the dye. The sensor shows sufficient repeatability, selectivity, operational lifetime of 8 weeks, and a fast response of less then 30 s. NO2− can be determined in the range between 1.0×10−6 and 1.0×10−4 mol l−1 with a detection limit of 8.0×10−7 mol l−1 at pH of 2.0. The quenching mechanism is discussed. Most commonly coexisting ions do not interfer with the NO2− assay.