Selective spectrofluorimetric determination of sulfide ion using manganese doped ZnS quantum dots as luminescent probe

This work reports a spectrofluorimetric method for selective and sensitive determination of sulfide ion in aqueous solution. The ultra-small zinc sulfide quantum dots (QDs) doped with manganese (ZnS:Mn) were synthesized by using a simple and fast procedure based on the co-precipitation of nanoparticles in aqueous solution in the presence of 2-mercaptoethanol, as capping agent. The nanoparticles have exhibited two strong fluorescent emissions at about 424 and 594 nm. Luminescent surface-capped ZnS:Mn QDs, with particle size below 5 nm, have been applied for determination of sulfide anions in water samples. Under the optimum conditions, the fluorescence intensity of ZnS:Mn QDs is linearly proportional to the sulfide ion concentration in the range 1.2 × 10−6 to 2.6 × 10−5 mol L−1 with a detection limit as 3.3 × 10−7 mol L−1. The relative standard deviation for five replicate measurements (for 8.0 × 10−6 mol L−1 of S2−) was obtained to be 2.6%. It was founded that the interference of the other anions was negligible on the quantitive determination of sulfide ion.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of ultra-small Mn doped ZnS quantum dots at room temperature. ► Novel luminescent probe for determination of sulfide ion in aqueous solutions. ► High selectivity of the designed optical sensor based on doped QDs. ► Sensitive determination of sulfide ion by fluorescence quenching.