Synchronous determination of mercury (II) and copper (II) based on quantum dots-multilayer film

A sensitive sensor for mercury (II) and copper (II) synchronous detection was established via the changed photoluminescence of CdTe quantum dots (QDs) multilayer films in this work. QDs were deposited on the quartz slides to form QDs-multilayer films by electrostatic interactions with poly(dimethyldiallyl ammonium chloride) (PDDA). Hg(2+) or Cu(2+) could quench the photoluminescence of the QDs-multilayer films, and glutathione (GSH) was used to remove Hg(2+) or Cu(2+) from QDs-multilayer films due to strong affinity of GSH-metal ions, which resulted in the recovered photoluminescence of QDs-multilayer films. There are good linear relationships between the metal ions concentration and the photoluminescence intensity of QDs in the quenched and recovered process. It was found that the Stern-Volmer constants for Hg(2+) are higher than that for Cu(2+). Based on different quenching and recovery constant between Hg(2+) and Cu(2+), the synchronous detection of Hg(2+) and Cu(2+) can be achieved. The linear ranges of this assay were obtained from 0.005 to 0.5 μM for Hg(2+) and from 0.01 to 1 μM for Cu(2+), respectively. And the artificial water samples were determined by this method with satisfactory results, the recoveries for Hg(2+) and Cu(2+) ions were found in the range of 90.4-106.4%. To the best of our knowledge, it is the first report about the synchronous detection of Hg(2+) and Cu(2+) by using quenched and recovered photoluminescence of quantum dots multilayer films.