Rapid determination of melamine in milk using water-soluble CdTe quantum dots as fluorescence probes

Abstract

Water-soluble CdTe quantum dots of different sizes capped with thioglycolic acid (TGA-CdTe QDs) were synthesised via a microwave-assisted method. It was found that melamine could quench the fluorescence emission of TGA-CdTe QDs in aqueous solution. Based on this, a novel method for the determination of melamine has been developed. Under optimum conditions, the fluorescence intensity of TGA-CdTe QDs versus melamine concentrations gave a linear response according to the Stern–Volmer equation. The proposed method has been successfully used to detect melamine in liquid milk with a detection limit of 0.04 mg L⁻¹, and the whole process including sample pre-treatment could be accomplished within 30 min. The obvious merits provided by this method, such as simplicity, rapidity, low cost and high sensitivity would make it promising for on-site screening of melamine adulterant in milk products. The possible mechanism involved in the interaction of melamine with TGA-CdTe QDs is discussed.

Keywords:

• CdTe quantum dots
• melamine
• fluorescence quenching
• liquid milk

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (No. 20905031) and the research start-up fund of Jilin University (No. 4305050102H6).

Notes

Minwei Zhang and Hong Ping contributed equally to this work.

Additional information

Notes on contributors

Hong Ping

Minwei Zhang and Hong Ping contributed equally to this work.