Determining local concentrations of the analytes in state-of-the-art microreactors is essential for the development of optimized and safe processes. However, the selective, parallel monitoring of all relevant reactants and products in a multianalyte environment is challenging. Electrochemical microsensors can provide unique information on the reaction kinetics and overall performance of the hydrogen peroxide synthesis process in microreactors, thanks to their high spatial and temporal resolution and their ability to measure in situ, in contrast to other techniques. We present a chronoamperometric approach which allows the selective detection of the dissolved gases hydrogen and oxygen and their reaction product hydrogen peroxide on the same platinum microelectrode in an aqueous electrolyte. The method enables us to obtain the concentration of each analyte using three specific potentials and to subtract interfering currents from the mixed signal. While hydrogen can be detected independently, no potentials can be found for a direct, selective measurement of oxygen and hydrogen peroxide. Instead, it was found that for combined signals, the individual contribution of all analytes superimposes linearly additive. We showed that the concentrations determined from the subtracted signals correlate very well with results obtained without interfering analytes present. For the first time, this approach allowed the mapping of the distribution of the analytes hydrogen, oxygen, and hydrogen peroxide inside a multiphase membrane microreactor, paving the way for online process control.

中文翻译：

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微反应器中H ₂，O ₂和H ₂ O _2的原位映射：并行的选择性多分析物检测方法

确定最先进的微反应器中分析物的局部浓度对于开发优化和安全的过程至关重要。然而，在多分析物环境中对所有相关反应物和产物的选择性，平行监测是具有挑战性的。与其他技术相比，电化学微传感器具有高的时空分辨率和现场测量能力，因此可以提供有关微反应器中过氧化氢合成过程的反应动力学和整体性能的独特信息。我们提出了一种计时电流法，该方法可以选择性地检测在水性电解质中同一铂微电极上溶解的气体中的氢气和氧气及其反应产物过氧化氢。该方法使我们能够使用三个特定电势获得每种分析物的浓度，并从混合信号中减去干扰电流。尽管可以独立检测氢气，但找不到直接，选择性地测量氧气和过氧化氢的电位。相反，发现对于组合信号，所有分析物的单独贡献线性叠加。我们表明，从减去的信号中确定的浓度与在不干扰分析物存在的情况下获得的结果非常相关。该方法首次允许在多相膜微反应器内绘制分析物氢，氧和过氧化氢的分布图，为在线过程控制铺平了道路。