title: An ultrasensitive method for the determination of melamine using cadmium telluride quantum dots as fluorescence probes.
abstract: An ultrasensitive and simple method for the determination of melamine was developed based on the fluorescence quenching of thioglycolic acid (TGA) capped CdTe quantum dots (QDs) at pH 11.0. In strong alkaline aqueous solution, the selectivity of the method has been greatly improved due to most heavy metal ions show no interference as they are in the precipitation form or in their anion form. Furthermore, CdTe quantum dots have higher quantum yields at higher pH. The method has a wider concentration range and lower detection limit. The influence factors on the determination of melamine were investigated and the optimum conditions were determined. Under optimum conditions, the fluorescence intensity change of TGA coated CdTe quantum dots was linearly proportional to melamine over a concentration range from 1.0×10(-11) to 1.0×10(-5) mol L(-1) with a correlation coefficient of 0.9943 and a detection limit of 5×10(-12) mol L(-1). The mechanism of fluorescence quenching of the QDs has been proposed based on the infrared spectroscopy information and electrophoresis experiments in presence of melamine under alkaline condition. The proposed method was employed to detect trace melamine in milk powder and pet feeds with satisfactory results.
authors.affiliation: School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, PR China; Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, Hunan University of Science and Technology, Xiangtan 411201, PR China.
authors.forename: Xiafei
authors.initials: X
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.forename: Huiyan
authors.initials: H
authors.lastname: Kuang
authors.forename: Lei
authors.initials: L
authors.lastname: Feng
authors.forename: Shoujun
authors.initials: S
authors.lastname: Yi
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xia
authors.forename: Haowen
authors.initials: H
authors.lastname: Huang
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Chunran
authors.initials: C
authors.lastname: Tang
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Zeng
keywords: Cadmium telluride quantum dots; Fluorescence probe; High selectivity; Melamine; Ultrasensitive determination