Facile synthesis of N-acetyl-l-cysteine capped ZnS quantum dots as an eco-friendly fluorescence sensor for Hg2+

This paper described an investigation of a novel eco-friendly fluorescence sensor for Hg 2+ ions based on N-acetyl- l -cysteine (NAC)-capped ZnS quantum dots (QDs) in aqueous solution. By using safe and low-cost materials, ZnS QDs modified by NAC were easily synthesized in aqueous medium via a one-step method. The quantitative detection of Hg 2+ ions was developed based on fluorescence quenching of ZnS QDs with high sensitivity and selectivity . Under optimal conditions, its response was linearly proportional to the concentration of Hg 2+ ions in a range from 0 to 2.4   ×   10 −6   mol   L −1 with a detection limit of 5.0   ×   10 −9   mol   L −1 . Most of common physiologically relevant cations and anions did not interfere with the detection of Hg 2+ . The proposed method was applied to the trace determination of Hg 2+ ions in water samples. The possible quenching mechanism was also examined by fluorescence and UV–vis absorption spectra .