Chemical reactions conducted in different media (liquid phase, gas phase, or surface) drive developments of versatile techniques for the detection of intermediates and prediction of reasonable reaction pathways. Without sample pretreatment, ambient mass spectrometry (AMS) has been applied to obtain structural information of reactive molecules that differ in polarity and molecular weight. Commercial ion sources (e.g., electrospray ionization, atmospheric pressure chemical ionization, and direct analysis in real-time) have been reported to monitor substrates and products by offline reaction examination. While the interception or characterization of reactive intermediates with short lifetime are still limited by the offline modes. Notably, online ionization technologies, with high tolerance to salt, buffer, and pH, can achieve direct sampling and ionization of on-going reactions conducted in different media (e.g., liquid phase, gas phase, or surface). Therefore, short-lived intermediates could be captured at unprecedented timescales, and the reaction dynamics could be studied for mechanism examinations without sample pretreatments. In this review, via various AMS methods, chemical reaction monitoring and mechanism elucidation for different classifications of reactions have been reviewed. The developments and advances of common ionization methods for offline reaction monitoring will also be highlighted.

中文翻译：

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通过环境质谱法监测化学反应

在不同介质（液相、气相或表面）中进行的化学反应推动了用于检测中间体和预测合理反应途径的通用技术的发展。在没有样品预处理的情况下，环境质谱 (AMS) 已用于获取极性和分子量不同的反应分子的结构信息。据报道，商业离子源（例如，电喷雾电离、大气压化学电离和实时直接分析）通过离线反应检查来监测底物和产物。而短寿命活性中间体的截留或表征仍然受到离线模式的限制。值得注意的是，在线电离技术对盐、缓冲液和 pH 值具有很高的耐受性，可以实现在不同介质（例如液相、气相或表面）中进行的正在进行的反应的直接采样和电离。因此，可以在前所未有的时间尺度上捕获短寿命中间体，并且可以在没有样品预处理的情况下研究反应动力学以进行机理检查。在这篇综述中，通过各种 AMS 方法，对不同反应分类的化学反应监测和机理阐明进行了综述。还将重点介绍用于离线反应监测的常用电离方法的发展和进步。并且可以在没有样品预处理的情况下研究反应动力学以进行机理检查。在这篇综述中，通过各种 AMS 方法，对不同反应分类的化学反应监测和机理阐明进行了综述。还将重点介绍用于离线反应监测的常用电离方法的发展和进步。并且可以在没有样品预处理的情况下研究反应动力学以进行机理检查。在这篇综述中，通过各种 AMS 方法，对不同反应分类的化学反应监测和机理阐明进行了综述。还将重点介绍用于离线反应监测的常用电离方法的发展和进步。