制备了性能优良的CdS量子点,量子点在水相中是高度单分散的.前人的研究表明,量子点的荧光发射对金属离子非常敏感,很容易被金属离子猝灭.根据这种现象研究了CdS量子点的表面对铅离子吸附的影响因素和机制.结果表明,下面的几个因素对荧光猝灭有主要的影响:溶液的酸度,量子点浓度,附着在量子点表面的铅离子的量.实验数据显示,CdS量子点表面对铅离子的吸附符合Langmuir等温吸附方程,c/ΔF与铅离子的浓度c是直线关系,浓度范围达到6个数量级.当在较小的浓度1×10-8~1×10-9mol/L时,ΔF与铅离子浓度c也是直线关系,线性相关系数为0.962 5,在此基础上,建立了铅离子的定量分析方法,方法的检出限为6.0×10-10 mol/L,相对标准偏差为2.5%,回收率为88.4%~107.2%.
In this paper,the mono-dispersed CdS quantum dots(QDS)were prepared in water.The fluorescence of the CdS QDs could be intensely quenched by the Pb2+,and the quenching effect was used to study the adsorption behavior of the Pb2+on the QDs’ surface.The result showed that the quenching effect was strongly influenced by the pH value and the QDs concentration,and involved the number of the Pb2+ adsorbed on the QDs’ surface.The adsorption behavior of the Pb2+ was consistent with the Langmuir isotherm equation,the relationship between the c/ΔF and c was linear,when the concentration of the Pb2+ was between 10-9 and 10-3mol/L.According to the Langmuir isotherm equation,the relationship of theΔF and c was also found to be linear at the low Pb2+ concentration of 1×10-8~1×10-9mol/L.And it was possible to determine the Pb2+concentration by using the line as the standard line.The detect limit was as low as 6.0×10-10 mol/L,the RSD was 2.5%,and the recovery rate was 88.4%~107.2%.
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