四(三羟甲基氨基甲烷)合铜(Ⅱ)电催化联吡啶钌/二氧化硅复合纳米粒子电化学发光分析特性研究

Investigation into Electrogenerated Chemiluminescence Behavior of Tris(bipyridine)ruthenium(Ⅱ)/silica Nanoparticles Electrocatalyzed by Cu(tris(hydroxymethyl)aminomethane)_4^(2+) Complex

水分子与联吡啶钌(Ru(bpy)32+)之间的电化学发光(ECL)反应早已被人们发现,但其增敏Ru(bpy)32+电化学发光信号的能力不强,很难实现分析应用.我们发现四(三羟甲基氨基甲烷)合铜(Ⅱ)(Cu(Tris)42+)可电催化水的氧化反应生成活性中间产物羟基自由基(·OH),·OH能够快速进入二氧化硅基质,有效地增敏联吡啶钌/二氧化硅复合纳米粒子(RuSNPs)的电化学发光,并利用紫外-可见吸收光谱、电化学方法、电化学发光方法等研究了可能的电化学反应机理.基于以上研究,发展了一种以水分子作为共反应试剂,测定铜离子的电化学发光分析新方法.该方法在铜离子浓度为2.0×10-7~1.0×10-4mol/L的范围内,电化学发光强度与铜离子浓度呈现良好的线性,同时该方法具有很好的灵敏度和选择性,检出限(S/N=3)达到1.0×10-7mol/L,且Ca2+、Mg2+、Na+、Fe3+、Pb2+、Cd2+、Co2+、Ni2+、Mn2+等常见离子不干扰测定.使用该法对自来水和黑河水样中铜离子含量进行测定,分别往两个水样中加入2~3倍的铜离子标准溶液,其加标回收率在97.0%~102.5%之间;与原子吸收分光光度法对比,相对误差分别为4.1%和4.7%,说明该方法测定结果具有一定的可靠性.

Although many electrogenerated chemiluminescence （ECL） co-reactants, such as tripropylamine （TPA） and ox- alic acid, have been applied in Tris（bipyridine）ruthenium（II）/silica nanoparticles （Ru（bpy）3^2＋/silica nanoparticles, RuS NPs） ECL system, the poor diffusion behavior of these co-reactants in silica matrix as well as its toxic disadvantages limited their further ECL analytical application. Therefore, it was very meaningful to explore a new type of co-reactant in RuS NPs ECL system for obtaining a good analytical result. In this paper, we found that the electrochemical oxidation reaction of H20 could be catalyzed by Cu（Tris）4^2＋ （Tris（hydroxymethyl）aminomethane, Tris） complexes and produce the intermediate （.OH）. The ECL of Ru（bpy）3^2＋-doped RuS NPs could be induced by .OH and produce the strong ECL signals. The possible ECL mecha- nism was investigated by ultraviolet-visible （UV-vis） absorption spectrum, electrochemical methods and ECL methods. It may be that when Cu^2＋ was added into the Tris-HC1 solution, it would combine with the amino of Tris to form Cu（TrJs）4^2＋ complexes; in the subsequent ECL reaction process, Ru（bpy）3^2＋ inside RuS NPs near by the surface of electrode was firstly oxidized to Ru（bpy）3^3＋. At the same time, the reduction reaction of Ru（bpy）3^3＋ would catalyze the oxidization of Cu（Tris）4^2＋ to generate the Cu（Tris）4^3＋; then, the reduction of Cu（Tris）4^3＋ would catalyze the electrochemical oxidation reaction of H20 and was accompanied by the generation of 02 and strong reducing agents （.OH）. On the one hand, the silica substrate could protect Ru（bpy）3^2＋-doped RuS NPs from 02 interference, and avoid the quenching effect of Ru（bpy）3^2＋ ECL induced by 02. On the other hand, .OH can rapidly go through the silica substrate and react with the oxidation state of Ru（bpy）3^3＋ inside of RuS NPs because it is a kind of neutral group. Based on these findings, we develop a new ECL method for sensitive detection of Cu^2＋ using H20 molecular as a co-reacant. Under the optimal conditions, the proposed method achieved a detection limit of 1.0Х l0^-7 mol/L with RSD of less than 5.0%.