A Fluorescent Chemosensor Based on Schiff Base for the Determination of Zn2+, Cd2+and Hg2+

Metal complexes were obtained by the reaction of zinc, cadmium and mercury(II) salts with Schiff base HL (N(salicylidene)benzylamine). HL was synthesized by the condensation reaction of benzylamine and 2-hydroxybenzaldehyde. The fluorescence properties of the Schiff base and its metal complexes were studied in ethanol-water solutions. HL was examined for its utility as a fuorescent chemosensor for the determination of Zn2+, Cd2+ and Hg2+ in aqueous samples. The HL chemosensor was found to be sensitive to Zn2+, Cd2+ and Hg2+ than some metal ions and its complexes emitted strong fluorescence at 452 nm for Zn2+ at 474 nm for Cd2+ and at 491 nm for Hg2+, respectively. It was determined that HL forms complexes with a ratio of 2:1 for Zn2+ and Hg2+ and with a ratio of 1:1 for Cd2+ by Job plots. For the detection of Zn2+, Cd2+ and Hg2+ in aqueous samples, pH, solvent type and ligand concentration were optimized for an analytical method based on HL chemosensor. HL gave a wide range of linearity with Zn2+, Hg2+ and Cd2+, the limit of detection was found to be 2.7 x 10(-7) M, 7.5 x 10(-7) M and 6.0 x 10(-7) M, respectively.