Determination of Cadmium(Ⅱ) with Cu-Doped ZnSe Quantum Dots as Fluorescence Probe

A method for determination of cadmium(Ⅱ) with Cu-doped ZnSe quantum dots (ZnSe/Cu QDs) as fluorescence probe was proposed based on the fluorescence quenching effect of ZnSe/Cu QDs with cadmium(Ⅱ). ZnSe/Cu QDs modified with mercaptopropionic acid was synthesized with microwave-assisted heating in water solution. Interaction between ZnSe/Cu QDs and cadmium(Ⅱ) was investigated by fluorescence spectra and UV spectra. Cadmium(Ⅱ) was determined in Tris-HCl buffer solution of pH 7.4 and 1.5×10-4mol·L-1 ZnSe/Cu QDs solution. Linear relationship between values of fluorescence quenching intensity of ZnSe/Cu QDs and mass concentration of cadmium(Ⅱ) was obtained in the range of 0.025-0.40 mg·L-1, with detection limit (3s/k) of 0.021 6 mg·L-1. The proposed method was used to determination of water samples with values of recovery of 98.0% and 102%. Precision of the method was tested with 0.15 mg·L-1 cadmium(Ⅱ) standard solution for 11 determination, value of RSD found was 6.7%.