CdTe量子点荧光猝灭法测定铜离子的研究

Studies on Fluorescence Quenching Method for the Determination of Copper Ions with CdTe Quantum Dots

以巯基乙酸为稳定剂,在水溶液中一步合成了CdTe量子点.以该量子点为荧光探针,基于荧光猝灭法对Cu2+离子进行了定量检测.考察了缓冲体系、缓冲液浓度、缓冲液pH值、反应时间、量子点浓度等多种因素的影响,在0.033mol/L、pH值为5.91的磷酸二氢钾磷酸氢二钠缓冲液中,当量子点浓度为3.8×10-4mol/L、反应时间为30min时,该方法的线性区间为2～200μg/L,检测下限为0.29μg/L.具体解释了量子点荧光猝灭,是由于价带电子激发到导带以后被表面结合的Cu2+离子捕获而产生的结果,并利用光解实验进一步验证了这一机理.

<Abstrcat>CdTe quantum dots were synthesized in aqueous solution with thioglycolic acid as the stabilizer. A new approach was developed for the sensitive and selective determination of copper ions with quantum dots as fluorescence probes. Different influencing factors were studied, including the concentration and pH of buffer, reacting time and quantum dots concentration. In 0.033 mol/L KH_2PO_4-Na_2HPO_4 with pH 5.91, when the concentration of quantum dots was 3.8×10^(-4) mol/L and the reacting time was 30 minutes, the relative fluorescence intensity decreased linearly with the copper ions' concentration in the range of 2 to 200 μg/L. The detection limit was 0.29 μg/L. Based on the charge-transfer quenching mechanism, the copper ions bound onto the surface of the quantum dots could absorb electrons from valance band, which resulted in the quenching of quantum dots. This was proved by photolysis experiments.