A selective determination of copper ions in water samples based on the fluorescence quenching of thiol-capped CdTe quantum dots

CdTe quantum dots (QDs) capped with different stabilizers, i.e. thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA) and glutathione (GSH) were investigated as fluorescent probes for the determination of Cu2+. The stabilizer was shown to play an important role in both the sensitivity and selectivity for the determination of Cu2+. TGA-capped CdTe QDs showed the highest sensitivity, followed by the MPA and GSH-capped CdTe QDs, respectively. The TGA- and MPA-capped CdTe QDs were not selective for Cu2+ that was affected by Ag+. The GSH-capped CdTe QDs were insensitive to Ag+ and were used to determine Cu2+ in water samples. Under optimal conditions, quenching of the fluorescence intensity (F-0/F) increased linearly with the concentration of Cu2+ over a range of 0.10-4.0 mu g/mL and the detection limit was 0.06 mu g/mL. The developed method was successfully applied to the determination of Cu2+ in water samples. Good recoveries of 93-104%, with a relative standard deviation of < 6% demonstrated that the developed simple method was accurate and reliable. The quenching mechanisms were also described. Copyright (c) 2015 John Wiley & Sons, Ltd.