迷迭香酸的CdTe量子点荧光探针同步荧光法测定

Synchronous Fluorescence Determination of Rosmarinic Acid with Surface-modified CdTe Quantum Dots as a Fluorescence Probe

基于迷迭香酸对CdTe量子点荧光的猝灭效应，建立了一种高灵敏度的测定微量迷迭香酸的同步荧光法。在pH5．7的缓冲溶液中，当固定波长差为210nm时，CdTe量子点的同步荧光最大发射波长位于320nm。在最佳实验条件下，迷迭香酸质量浓度在0．36～11．52mg·L^-1（1．00×10^-6～3．20×10^-5mol／L）范围与CdTe量子点的同步荧光强度存在良好的线性关系。其线性回归方程为IF^0／IF=0．9317＋0．1289ρ（mg·L^-1），相关系数r=0．9982，检出限为0．16mg·L^-1。10次重复测定2．16mg·L^-1的迷迭香酸，相对标准偏差为2．8％。同时对其同步荧光猝灭机理进行了探讨。

The CdTe quantum dots（QDs） were synthesized in aqueous solution using thioglycolic acid as stabilizing agents. Based on the fluorescence quenching of CdTe QDs by rosmarinic acid, a novel method for determination of rosmarinic acid was developed. When A,△λ = 210 nm, the maximum emission wavelength of synchronous fluorescence was 320 nm in pH 5.7 buffer. Under the optimal conditions, the synchronous fluorescence intensity showed a good linearity over the concentration of rosmarinic acid in the range of 0. 36 -11. 52 mg· L^-1（1.00×10^-6～3.20×10^-5mol/L）. The linear equation was IF^0/IF =0. 931 7 ＋ 0. 128 9 ρ（ mg· L^-1 ） with a correlation coefficient of 0. 998 2. The detection limit（S/N = 3 ） was 0. 16 mg· L^-1 The relative standard deviation of ten replicate measurements for 2. 16 mg· L^-1 rosmarinic acid was 2.8% . The interaction of rosmarinic acid and CdTe QDs was studied by fluorescence quenching, and the binding constant was obtained to be 9.27 × 10^5 L/mol, indicating that rosmarinic acid could strongly bind to CdTe QDs. Forthermore, the possible synchronous fluorescence quenching mechanism was discussed.