CdTe/CdS量子点荧光猝灭法测定十六烷基三甲基溴化铵

Determination of CTAB by fluorescence quenching of CdTe/CdS quantum dots

以巯基乙酸为稳定剂,在水溶液中合成了CdTe/CdS量子点,基于十六烷基三甲基溴化铵（CTAB）与CdTe/CdS量子点的荧光猝灭作用,建立了用CdTe/CdS量子点作为荧光探针测定水中微量十六烷基三甲基溴化铵的新方法。考察了缓冲溶液、pH和量子点浓度等因素对体系荧光强度的影响。结果表明,在pH为6.8的磷酸二氢钾-硼砂缓冲溶液中,当CdTe/CdS量子点浓度为3.75×10-4mol/L时,体系的相对荧光强度与十六烷基三甲基溴化铵的浓度在5.49×10-7~4.12×10-5mol/L范围内呈现良好的线性关系,相关系数为0.999 7,检出限为5.43×10-8mol/L。方法应用于水中微量十六烷基三甲基溴化铵测定,回收率在96.7%~101.7%。

The water-soluble CdTe/CdS quantum dots（QDs） modified with thioglycolic acid was synthesized.Based on the significant quenching effect of cetyltrimethylammonium bromide（CTAB） on the fluorescence of CdTe/CdS quantum dots in aqueous solution,a novel method for the determination of cetyltrimethylammonium bromide（CTAB） has been developed.The effects of buffer solution,pH value and quantum dots concentration on the fluorescence intensity of CdTe/CdS QDs-CTAB system were discussed.Under optimum conditions wherein the pH of KH2PO4-Na2B4O7 buffer medium was 6.8 and the concentration of CdTe/CdS quantum dots was 3.75×10-4 mol/L,the relative fluorescence intensity was linearly proportional to the cetyltrimethylammonium bromide concentration in the range from 5.49×10-7 to 4.12×10-5 mol/L with a correlation coefficient of 0.999 7,and the detection limit was 5.43×10-8 mol/L for CTAB.The proposed method has been applied to the determination of cetyltrimethylammonium bromide in water samples with the recoveries reaching 96.7%～101.7%.The possible fluorescence quenching mechanism was discussed.