油溶性CdSe量子点荧光探针直接检测农药水胺硫磷

基于农药水胺硫磷对油溶性CdSe量子点荧光猝灭的现象，建立了一种简单、快速、直接检测农药水胺硫磷的新方法。在最佳实验条件下，油溶性CdSe量子点的荧光猝灭程度与水胺硫磷浓度在2.30×10-7～1.09×10-5 mol·L-1范围内呈较好的线性关系，相关系数为0.999 9，对水胺硫磷的检出限为1.1×10-7 mol·L-1。本法已成功用于大米和小麦面粉样品中水胺硫磷农药残留的检测，加入回收率在93.3%～105.0%之间，结果满意。结合紫外-可见吸收光谱及时间分辨荧光光谱，探讨了水胺硫磷对油溶性CdSe量子点荧光猝灭的机理。研究结果表明，水胺硫磷能有效改变油溶性CdSe量子点的表面状态，增大了表面缺陷和非辐射重组的发生，从而使油溶性CdSe量子点的荧光猝灭。

Direct Determination of Isocarbophos by Using Oil-Soluble CdSe Quantum Dots as Fluorescence Probe

A simple, rapid and direct approach to isocarbophos determination was developed based on the fluorescence quenching of oil-soluble CdSe quantum dots by isocarbophos. Under the optimized conditions, the linear range of oil-soluble CdSe QDs fluorescence intensity versus the concentration of isocarbophos was 2.30×10-7～1.09×10-5 mol·L-1, with a correlation coefficient of 0.999 9 and a limit of detection of 1.1×10-7 mol·L-1. The proposed method has been applied to the determination of isocarbophos in rice and wheat flour with standard recoveries of 93.3%～105.0%. The fluorescence quenching mechanism was further investigated by using UV-Vis absorption spectra and time-resolved fluorescence spectrum. The results indicated that the fluorescence quenching of oil-soluble CdSe QDs by isocarbophos was caused by the change of the surface state which resulted in the enhancement of the surface defect and the occurrence of the non-radiational recombination.