氨基化碳量子点荧光猝灭法测定铜

Determination of copper by amino-functional carbon quantum dots fluorescence quenching method

利用水热法以葡萄糖为碳源制备碳量子点,并用乙二胺使其表面氨基化。根据铜离子可使氨基化碳量子点荧光发生猝灭,建立了荧光猝灭法测定痕量铜的新方法。在比色管中分别加入1.0mL氨基化碳量子点和不同浓度的铜离子溶液、1.0mL pH 7.7磷酸盐缓冲溶液,用水定容到5mL,混合均匀室温反应20min后在最大激发/发射波长(λ_(ex)/λ_(em))为465nm/522nm处测定体系的相对荧光强度。结果发现,铜离子浓度在4.0×10-6~3.8×10-5 mol/L范围内与其相对荧光强度具有良好的线性关系,相关系数为0.994 6,方法检出限为4.5×10-7mol/L。采用实验方法对本地灌溉水和耕地土壤中痕量铜进行测定,结果与原子吸收光谱法(AAS)基本一致,相对标准偏差(RSD,n=5)为3.2%和2.3%,回收率为92%~108%。

The carbon quantum dots were prepared by hydrothermal method with glucose as carbon source. Then its surface amination was conducted with ethanediamine. On the basis of fact that the fluorescence of aminated carbon quantum dots could be quenched by copper ions, a new determination method of trace cop-per by fluorescence quenching method was established. 1. 0 mL of aminated carbon quantum dots, the cop-per ion solution with various concentrations and 1. 0 mL of phosphate buffer solution at pH 7. 7 were added into colorimetric tube. The solution was diluted to 5 mL with water. After the solution was mixed uni-formly and reaction at room temperature for 20 min, the relative fluorescence intensity of testing system at the maximum excitation/emission wavelength of 465 nm/522 nm （Aex/Aem） was measured. The results showed that the concentration of copper ion in range of 4. 0 × 10-6-3. 8 × 10-5 mol/L was linear to its corre-sponding relative fluorescence intensity. The correlation coefficient was 0. 994 6. The detection limit was 4. 5 × 10^-7 mol/L. The proposed method was applied to the determination of trace copper in the local irri-gation water sample and arable soil sample. The results were consistent with those obtained by atomic ab-sorption spectrometry（AAS）. The relative standard deviations （RSD, 5） were 3.2% and 2. 3%. The recoveries were between 92% and 108%.