Fluorescent sensor for selective determination of copper ion based on N-acetyl-l-cysteine capped CdHgSe quantum dots

Using N-acetyl-l-cysteine as a stabilizer, well water-dispersed, high-quality and stable CdHgSe quantum dots were facilely synthesized via a simple aqueous phase method. The as-prepared N-acetyl-l-cysteine capped CdHgSe quantum dots were thoroughly characterized by transmission electron microscopy, X-ray diffraction spectroscopy and FTIR. A fluorescent sensor for selective determination of copper ions was developed using N-acetyl-l-cysteine capped CdHgSe quantum dots as fluorescent probe. The fluorescence intensity of N-acetyl-l-cysteine capped CdHgSe quantum dots decreased when interacted with copper ions due to the formation of coordination complex and aggregates. The method possesses high selectivity and is not influenced by some potential interferences such as Ag+, Zn2+, Co2+ and Ni2+. Under the optimal conditions, the change of fluorescence intensity (ΔI) was linearly proportional to the concentration of copper ions in the range of 1.0×10−9-4.0×10−7 mol L−1, with a detection limit as low as 2.0×10−10 mol L−1 (S/N=3). The developed method had been successfully employed to determine Cu2+ in shrimp and South-lake water samples, and the results were verified by atomic absorption spectroscopy. The fluorescent sensor was demonstrated to be selective, sensitive and simple for copper ion determination, and promise for practical applications.