Wang Guoqing, Lim Chaesung, Chen Lingxin, Chon Hyangah, Choo Jaebum, Hong Jongin, deMello Andrew J
Department of Applied Chemistry, Hanyang University, Ansan, 426-791, South Korea.
Anal Bioanal Chem. 2009 Aug;394(7):1827-32. doi: 10.1007/s00216-009-2832-7. Epub 2009 May 15.
We report a new method for the trace analysis of mercury (II) ions in water. The approach involves the use of droplet-based microfluidics combined with surface-enhanced Raman scattering (SERS) detection. This novel combination provides both fast and sensitive detection of mercury (II) ions in water. Specifically, mercury (II) ion detection is performed by using the strong affinity between gold nanoparticles and mercury (II) ions. This interaction causes a change in the SERS signal of the reporter molecule rhodamine B that is a function of mercury (II) ion concentration. To allow both reproducible and quantitative analysis, aqueous samples are encapsulated within nanoliter-sized droplets. Manipulation of such droplets through winding microchannels affords rapid and efficient mixing of the contents. Additionally, memory effects, caused by the precipitation of nanoparticle aggregates on channel walls, are removed since the aqueous droplets are completely isolated by a continuous oil phase. Quantitative analysis of mercury (II) ions was performed by calculating spectral peak area of rhodamine B at 1,647 cm(-1). Using this approach, the calculated concentration limit of detection was estimated to be between 100 and 500 ppt. Compared with fluorescence-based methods for the trace analysis of mercury (II) ions, the detection sensitivities were enhanced by approximately one order of magnitude. The proposed analytical method offers a rapid and reproducible trace detection capability for mercury (II) ions in water.
我们报道了一种用于水中汞（II）离子痕量分析的新方法。该方法涉及基于液滴的微流控技术与表面增强拉曼散射（SERS）检测相结合。这种新颖的组合实现了对水中汞（II）离子的快速且灵敏的检测。具体而言，汞（II）离子检测是利用金纳米颗粒与汞（II）离子之间的强亲和力来进行的。这种相互作用导致报告分子罗丹明B的SERS信号发生变化，该变化是汞（II）离子浓度的函数。为了实现可重复和定量分析，将水性样品封装在纳升大小的液滴中。通过蜿蜒的微通道对这些液滴进行操控，可实现内容物的快速高效混合。此外，由于纳米颗粒聚集体在通道壁上沉淀而导致的记忆效应得以消除，因为水性液滴被连续的油相完全隔离。通过计算罗丹明B在1647 cm⁻¹处的光谱峰面积对汞（II）离子进行定量分析。采用这种方法，计算得出的检测浓度下限估计在100至500 ppt之间。与基于荧光的汞（II）离子痕量分析方法相比，检测灵敏度提高了约一个数量级。所提出的分析方法为水中汞（II）离子提供了一种快速且可重复的痕量检测能力。
