Research Center for Biomimetic Functional Materials and Sensing Devices, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, PR China.
Anal Chem. 2013 Mar 5;85(5):2673-80. doi: 10.1021/ac303143x. Epub 2013 Feb 15.
In recent decades, electrochemical detection of arsenic(III) has been undergoing revolutionary developments with higher sensitivity and lower detection limit. Despite great success, electrochemical detection of As(III) still depends heavily on noble metals (predominantly Au) in a strong acid condition, thus increasing the cost and hampering the widespread application. Here, we report a disposable platform completely free from noble metals for electrochemical detection of As(III) in drinking water under nearly neutral condition by square wave anodic stripping voltammetry. By combining the high adsorptivity of Fe3O4 microspheres toward As(III) and the advantages of room temperature ionic liquid (RTIL), the Fe3O4-RTIL composite modified screen-printed carbon electrode (SPCE) showed even better electrochemical performance than commonly used noble metals. Several ionic liquids with different viscosities and surface tensions were found to have a different effect on the voltammetric behavior toward As(III). Under the optimized conditions, the Fe3O4-RTIL composites offered direct detection of As(III) within the desirable range (10 ppb) in drinking water as specified by the World Health Organization (WHO), with a detection limit (3σ method) of 8 × 10(-4) ppb. The obtained sensitivity was 4.91 μA ppb(-1), which is the highest as far as we know. In addition, a possible mechanism for As(III) preconcentration based on adsorption has been proposed and supported by designed experiments. Finally, this platform was successfully applied to analyzing a real sample collected from Inner Mongolia, China.
近几十年来，电化学检测砷（III）技术取得了革命性的发展，具有更高的灵敏度和更低的检测限。尽管取得了巨大的成功，但电化学检测 As(III) 仍然严重依赖于贵金属（主要是 Au）在强酸条件下，从而增加了成本并阻碍了其广泛应用。在这里，我们报告了一种完全不含贵金属的一次性平台，用于在近中性条件下通过方波阳极溶出伏安法电化学检测饮用水中的 As(III)。通过结合 Fe3O4 微球对 As(III) 的高吸附性和室温离子液体（RTIL）的优点，Fe3O4-RTIL 复合修饰丝网印刷碳电极（SPCE）的电化学性能甚至优于常用的贵金属。研究发现，几种具有不同粘度和表面张力的离子液体对 As(III) 的伏安行为有不同的影响。在优化条件下，Fe3O4-RTIL 复合材料在饮用水中直接检测到理想范围内（10 ppb）的 As(III)，检测限（3σ 方法）为 8 × 10(-4) ppb。获得的灵敏度为 4.91 μA ppb(-1)，据我们所知，这是迄今为止最高的。此外，还提出了一种基于吸附的 As(III)预浓缩的可能机制，并通过设计实验得到了支持。最后，该平台成功应用于分析来自中国内蒙古的实际样品。
