A simple polyethylenimine-salicylaldehyde fluorescence probe: sensitive and selective detection of Zn2+ and Cd2+ in aqueous solution by adding S2− ion

A novel fluorescence probe PEI-SA was synthesized and it can be used to detect Zn2+ and Cd2+, since metal-to-ligand complex composed by the metal ions and Schiff base formed. Meanwhile, adding S2− can lead to fluorescent quenching in Cd2+@PEI-SA but not in Zn2+@PEI-SA. This fluorescence switching method can detect Zn2+ and Cd2+ in parallel.