功能化纳米金用于水中痕量铬(Ⅵ)的比色测定

Colorimetric Determination of Trace Cr(Ⅵ) in Aqueous Solution by Functionalized Gold Nanoparticles

采用柠檬酸钠还原法制备了平均粒径为16nm的纳米金（AuNPs），用二硫苏糖醇（DTT）对AuNPs进行修饰，得到功能化的DTT—AuNPs。研究了DTT—AuNPs的紫外可见吸收光谱、Zeta电位及TEM。发现在弱酸性条件下，铬（Ⅵ）能引起DTr—AuNPs聚集，使其最大吸收峰发生红移，基于此建立了铬（Ⅵ）的比色测定方法。优化了DTT浓度、溶液pH，考察了其它金属离子的干扰。在最佳检测条件下，方法的线性范围为100～600nmol／L（r=0．9978），检出限为10nmol／L。将方法用于测定水库水中的痕量铬（Ⅵ），回收率为95％～115％。

The determination of trace Cr6＋ in waters is very important because of its highly carcinogenic and mutagenie effects. In this study, gold nanoparticles （AuNPs） with average diameter of 16 nm were synthesized with the citrate-mediated reduction of HAuCl4 and modified by 1, 4-dithioth- reito（DTY） containing two end thiols to achieve the functionalized DTT-AuNPs. DTT-AuNPs were characterized by UV visible absorption spectra, Zeta potentials and transmission electron microscopy （TEM）. A colorimetric method for the determination of trace Cr6＋ in waters was developed based on the aggregation of the DTT-AuNPs in weak acid media in the presence of trace Cr6 ＋ , which could lead to a red shift of the maximum absorption wavelength（from 520 nm to 650 nm） of the DTT-AuNPs and produce an obvious color change from wine-red to blue-purple. Some parameters affecting the determination, including the concentration of DTT and pH value were optimized. Under the optimized conditions, a good linear relationship （ r = 0. 997 8 ） was obtained between the ratio value of A650/520 and the concentration of Cr6 ＋ in the range of 100 -600 nmol/L, and the limit of detection （LOD） ibr Cr6＋ at a signal-to-noise ratio of 3 was 10 nmol/L. The detection system showed highly selective re- sponse toward Cr6＋ against other common metal cations such as Fe3＋ , Pb2＋ , Hg2＋ , Cr3＋ , Na ＋ , Mg2＋, Ca2＋, Ba2＋, Fe2＋, Co2＋, Ni2＋, Cu2＋, Zn2＋, Cd2＋and Al3 ＋ ions in waters. The proposed method was applied in the determination of trace Cr6 ＋ in reservoir water with recoveries of 95% - 115%.