对水热合成CdTe量子点的方法加以改进,并合成了用3-巯基丙酸(MPA)修饰的CdTe量子点(MPA-CdTe QD′s)。该量子点具有荧光特性,激发、发射波长分别为320,558 nm。试验了17种常见金属离子对此量子点荧光强度的影响,结果发现只有Cd(Ⅱ)离子对其荧光有增强作用;Hg(Ⅱ)、Cu(Ⅱ)、Ag(Ⅰ)则对其荧光有猝灭作用,加入适量抗坏血酸和碘化钾可消除这3种金属离子的荧光猝灭作用。试验在pH 6的缓冲介质中,以20 μL MPA-CdTe QD′s作为荧光探针,加入不同浓度的Cd(Ⅱ)离子并在反应6 min后,体系的荧光增强程度与Cd(Ⅱ)离子浓度在5.0×10-7~3.9×10-5mol·L-1范围内呈线性关系,检出限(3s/k)为4.8×10-7mol·L-1。

The hydrothermal method for preparation of CdTe QD′s was improved, and 3-mercaptopropionic acid (MPA) modified CdTe QD′s were prepared. As shown in the fluorescence spectra, λex and λem of MPA-CdTe QD′s were found at 320 nm and 558 nm respectively. 17 common metal ions were added to the fluorescence system to test for their effect on the fluorescence intensity of MPA-CdTe QD′s. It was shown that only Cd(Ⅱ) given enhancement effect on the fluorescence intensity while Hg(Ⅱ), Cu(Ⅱ) and Ag(Ⅰ) give quenching effect which can be eliminated by addition of ascorbic acid and KI. Cd(Ⅱ) solutions of various concentrations were added to the reaction system in a buffer medium of pH 6 with 20 μL of MPA-CdTe QD′s as fluorescence probe, after reacting for 6 min, values of fluorescence intensity measured were found to keep linear relationship with concentration of Cd(Ⅱ) in the range of 5.0×10-7-3.9×10-5mol·L-1. Detection limit (3s/k) found was 4.8×10-7mol·L-1.