Detection of copper ions and glutathione based on off-on fluorescent graphene quantum dots

We developed a rapid method to detect Cu²⁺ and glutathione(GSH)based on the fluorescence quenching-recovery properties of graphene quantum dots(GQDs), which were synthesized by the gentle oxidation of graphite powder. The results revealed that the fluorescence intensity of GQDs versus concentration of Cu²⁺ and GSH had good linearity, with the detection limits of 0. 01 and 0. 1 mmol/L, respectively. The fluorescence quenching was linearly proportional to the concentrations of Cu²⁺ ranging from 1. 0 to 10. 0 mmol/L; the fluorescence intensity was linearly enhanced with the concentrations of GSH ranging from 0. 1 to 1. 0 mmol/L. In addition, the method was successfully applied to the determination of real samples with recoveries falling between 93%-101% and 96%-107%, respectively. This method is simple, accurate and precise. There was no interference with other familiar co-existing metal ions and potential materials.