Application Of CdS Quantum Dots In Analytical Chemistry

Quantum dots have various effects, so the properties of them are different from corresponding body materials, such as wide excitation spectrum, narrow but symmetrical emission spectrum, high luminous efficiency and controllable emission wavelength as well as strong anti-photobleaching ability. In addition, compared with traditional organic dyestuff,the optical properties, the stability and biocompatibility of quantum dot are better. So,quantum dot can be widely applied to chemistry, biology, energy and photoelectric devices etc.Main research content of the thesis is as follows:(1) Make use of the fluorescence quenching effect of maltose on quantum dot to study the absorption behavior of maltose on the surface of quantum dot. Result shows that pH value and the concentration of the quantum dot significantly affect the fluorescence quenching effect on quantum dot and the latter is also related to the number of maltose molecules absorbing on the surface of the quantum dot, and the absorption of maltose molecules on the surface of the quantum dot corresponds to Langmuir isothermal absorption equation. According to Langmuir isothermal absorption equation, within a low concentration range, the relationship between ?F and concentration C has good linear relationship; a quantitative analysis method of maltose can be established with such kind of linear relationship and the detection limit reaches nmol level, and the interference effect of some materials is studied;(2) Based on the fluorescence quenching effect of lead ion on CdS quantum dot, the thesis studies the absorption behavior of lead ion on the surface of quantum dot and establishes a analytical method to detect trace lead ions in water quickly. The result shows that the fluorescence quenching effect on the quantum dot is apparently influence by pH value and the concentration of the quantum dot and is related to the number of lead ions absorbing to the surface of the quantum dot; the absorption of lead ion on the surface of CdS quantum dot corresponds to Langmuir isothermal absorption equation; within the range from 1×10-8 to1×10-9 mol?L-1, the relationship between ?F and concentration C has good linear relationship, correlation coefficient is 0.9774, the detection limit is 5.4×10-10, the recovery was between 98% and 106.5% and the relative standarddeviation is 2.9%.