Copper Ion Detection Method Based on a Quantum Dot Fluorescent Probe

The heavy metal ion Cu2+ was used as the research object in this study. Cu2+ was detected using a cysteine- and glutathione-modified cadmium telluride quantum dot solution. Compounds of Cu2+ and modified quantum dots on the surface caused the fluorescence quenching of quantum dots. A linear relationship existed between the concentration and the intensity of the change in fluorescence quenching. Using this linear relationship, the quantitative detection of the Cu2+ content in the solution by quantum dots was achieved; the detection band was 476-800 nm. Under optimized conditions, the detection limit of the method was 3.58×10-5 mol/L (S/N=3, n=11), and the linear range was 3×10-7 to 8×10-4 mol/L. In a certain experimental environment, standard normal variate preprocessing of the characteristic band and partial least squares modeling and analysis yielded good self-prediction and actual prediction abilities. The correction coefficient was 0.9006. The RMSEC was 8.83084 µmol/L, the determination coefficient of the validation set was 0.8686, and the RMSEP was 5.4320 µmol/L. The results showed that the modeling effect was good in the experiment, the operation was simple and convenient, and the experiment was fast, reliable, and nonpolluting, indicating that the method of detecting Cu2+ using a quantum dot fluorescent probe was feasible.