Synthesis of novel probe 2-chloro-6-methoxy-3-phenyl hydrazone quinoline and its application to detection of persulphate in aqueous ethanol solution by fluorescence turn on

Abstract

A highly sensitive and selective fluorimetric detection method has been developed for persulphate anion using fluorescence turn on of 2-chloro-6-methoxy-3-phenyl hydrazone quinoline (Cl-MPHQ) in aqueous ethanol solution. Cl-MPHQ is a weakly fluorescent compound synthesized via a one-step reaction of 2-chloro-6-methoxyquinoline-3-carboxyaldehyde (Cl-MQCA) and phenyl hydrazine. The treatment of Cl-MPHQ with persulphate ion in aqueous ethanol solution (1:1 V/V) generates fluorescent Cl-MQCA, through C=N bond cleavage. The fluorescence intensity increased linearly with the concentration of persulphate ion (0–100 µmol L−1). The detection limit of the method is 1 µmol L−1determined from the standard deviation of the blank signal (3σ). The relative standard deviation of the method is 3% for 20 µmol L−1 of persulphate ion. The proposed method is simple, sensitive and useful for selective detection of persulphate ion in an aqueous ethanol solution.