Concentration Enrichment in a Dissolving Microdroplet: Accessing Sub-nanomolar Electroanalysis.
Concentration Enrichment in a Dissolving Microdroplet: Accessing Sub-nanomolar Electroanalysis.
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DOI：
10.1021/acs.analchem.3c04971
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发表时间：
2024-03
影响因子：
7.4
通讯作者：
Ashutosh Rana;James H Nguyen;C. Renault;J. Dick
中科院分区：
文献类型：
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作者：
Ashutosh Rana;James H Nguyen;C. Renault;J. Dick
液滴蒸发以前曾被用作浓度富集策略;然而，所选择的测量技术需要在相当大的体积中进行定量。电化学最近已经成为一种方法，以稳健的探测体积，甚至下降到阿升（10-18 L）的水平。我们提出了一种基于微滴溶解的浓度富集策略，该微滴置于Au超微电极（半径为6.25 μm）表面。通过精确地定位一个1，2-二氯乙烷微滴上的超微电极与微量注射器，我们能够跟踪液滴的行为光学和电化学。由于液滴随时间自发溶解，考虑到1，2-二氯乙烷在水连续相中的相对溶解度，体积随时间的变化富集了液滴中氧化还原探针（Cp 2 *（Fe）II）的浓度。我们证明了强大的电化学检测到亚nM（800 pM）浓度的Cp 2 *（Fe）II。对于该液滴，800 pM仅构成约106个分子。我们在单盲研究中扩展了该策略以确定未知浓度，强调了新方法的前景。这些结果很容易将伏安定量带到亚μM范围。
Droplet evaporation has previously been used as a concentration enrichment strategy; however, the measurement technique of choice requires quantification in rather large volumes. Electrochemistry has recently emerged as a method to robustly probe volumes even down to the attoliter (10-18 L) level. We present a concentration enrichment strategy based on the dissolution of a microdroplet placed on the surface of a Au ultramicroelectrode (radius ∼ 6.25 μm). By precisely positioning a 1,2-dichloroethane microdroplet onto the ultramicroelectrode with a microinjector, we are able to track the droplet's behavior optically and electrochemically. Because the droplet spontaneously dissolves over time, given the relative solubility of 1,2-dichloroethane in the water continuous phase, the change in volume with time enriches the concentration of the redox probe (Cp2*(Fe)II) in the droplet. We demonstrate robust electrochemical detection down to sub-nM (800 pM) concentrations of Cp2*(Fe)II. For this droplet, 800 pM constitutes only about 106 molecules. We extend the strategy in a single-blind study to determine unknown concentrations, emphasizing the promise of the new methodology. These results take voltammetric quantification easily to the sub-μM regime.