Department of Chemistry, Chungbuk National University, Cheongju 28644, Republic of Korea.
Sensors (Basel). 2023 Feb 14;23(4):2157. doi: 10.3390/s23042157.
Herein, we report the electrochemical monitoring of attoliters of water droplets in an organic medium by the electrolysis of an extracted redox species from the continuous phase upon collisional events on an ultramicroelectrode. To obtain information about a redox-free water droplet in an organic solvent, redox species with certain concentrations need to be contained inside it. The redox species inside the droplet were delivered by a partitioning equilibrium between the organic phase and the water droplets. The mass transfer of the redox species from the surrounding organic phase to the droplet is very fast because of the radial diffusion, which resultantly establishes the equilibrium. Upon the collisional contact between the droplet and the electrode, the extracted redox species in the water droplets were selectively electrolyzed, even though the redox species in the organic continuous phase remained unreacted because of the different solvent environments. The electrolysis of the redox species in the droplets, where the concentration is determined by the equilibrium constant of the redox species in water/oil, can be used to estimate the size of single water droplets in an organic solution.
在此，我们报告了通过在微电极上的碰撞事件从连续相中提取的氧化还原物种的电解来在有机介质中对纳升级别的水滴进行电化学监测。为了获得有关有机溶剂中无氧化还原的水滴的信息，需要在其中包含具有一定浓度的氧化还原物种。通过有机相和水滴之间的分配平衡，将氧化还原物种输送到液滴内。由于径向扩散，氧化还原物种从周围有机相转移到液滴的传质非常快，从而建立了平衡。在液滴与电极之间发生碰撞接触时，即使由于溶剂环境的不同，有机连续相中的氧化还原物种仍未反应，但仍可选择性地电解水滴中的提取氧化还原物种。在这些液滴中，氧化还原物种的电解，其浓度由水/油中的氧化还原物种的平衡常数决定，可以用来估计有机溶液中单滴水滴的大小。
