Department of Chemistry, University of Cincinnati, 301 Clifton Court, Cincinnati, Ohio 45221-0172, USA.
Anal Chem. 2010 Mar 1;82(5):1720-6. doi: 10.1021/ac902243u.
Spectroelectrochemical sensors developed in our group achieve three modes of selectivity by combining electrochemistry, spectroscopy, and a chemically selective membrane in a single device. Analyte detection is based upon a change in the optical response due to the conversion of the analyte between two oxidation states that results from the cycling or stepping of the applied potential. We have demonstrated a novel approach to simultaneously detect two metals by combining optical stripping voltammetry for one metal (Pb(2+)) and the in situ ligand complexation in a film for the other metal (Fe(2+)). Using an indium tin oxide (ITO) sensor platform with a 50 nm Nafion film to preconcentrate the analytes, equimolar mixtures of Pb(2+) and Fe(2+) in 0.1 M sodium acetate buffer (pH 5) were detected. Pb(2+) was detected by optical stripping voltammetry, in which lead was deposited as metal on the ITO and detected by the optical change as it was removed by stripping. The ferrous ion was detected by the in situ ligand complexation method in which Fe(2+) was complexed with 2,2'-bipyridyl in the Nafion in the film to form an intense red complex that was detected by absorbance at 520 nm. Detection limits of 300 and 400 nM were obtained for Pb(2+) and Fe(2+), respectively. The presence of the film had no effect on the optical signal that results from the deposition and stripping of the Pb(2+). In addition, competition between the Pb(2+) and Fe(2+) for sites in the film and for the organic ligand was investigated.
我们小组开发的光谱电化学传感器通过将电化学、光谱学和化学选择性膜结合在单个设备中，实现了三种选择性模式。分析物的检测是基于光学响应的变化，这是由于施加的电位的循环或阶跃导致分析物在两种氧化态之间的转化。我们已经证明了一种通过结合光学剥离伏安法（用于一种金属（Pb(2+)）和原位配位体络合在薄膜中用于另一种金属（Fe(2+)）来同时检测两种金属的新方法。使用带有 50nm Nafion 膜的铟锡氧化物 (ITO) 传感器平台来预浓缩分析物，可以检测到 0.1M 乙酸钠缓冲液（pH5）中 Pb(2+)和 Fe(2+)的等摩尔混合物。Pb(2+)通过光学剥离伏安法检测，其中铅在 ITO 上沉积为金属，并通过其去除的剥离光学变化进行检测。亚铁离子通过原位配位体络合法检测，其中 Fe(2+)在薄膜中的 2,2'-联吡啶与配位体络合形成强烈的红色络合物，通过在 520nm 处的吸光度进行检测。对于 Pb(2+)和 Fe(2+)，分别获得了 300 和 400nM 的检测限。薄膜的存在对由 Pb(2+)的沉积和剥离引起的光学信号没有影响。此外，还研究了 Pb(2+)和 Fe(2+)之间在薄膜中和有机配体中的竞争。
