质谱（MS）是获取分子结构信息的最有效工具之一，在物质结构分析中占用重要的地位。近年来常压质谱（AMS）的发展为无需样品预处理、快速获取样品信息提供了有力工具，因而在对化学反应监测研究中具有潜在优势。与此同时，随着科学技术的发展和工业化进程的推进，反应监测也将对工业发展、过程控制、生物过程研究等领域的发展起到积极作用。基于此背景，本论文构建了三种常压质谱离子源，并将其应用于反应机理研究： （一） 多层液流萃取电喷雾离子源及FAD在葡萄糖氧化中的作用 黄素腺嘌呤二核苷酸（FAD）是葡萄糖氧化酶中存在于各个亚基中的辅酶分子，在葡萄糖催化氧化中具有电子转运的作用。然而该过程机理复杂，至今只是预测了中间产物的存在，仍缺乏直接证据，这也是机理研究的一个最大难题。在本工作中构建了一种多层液流萃取喷雾离子源（MF-EESI）完成了对葡萄糖酶催化氧化过程的分析，并研究了FAD在其中的作用。通过多层流体的共同作用，反应体系被抽提至毛细管尖端，形成雾滴的同时与甲醇喷雾充分作用提高了其离子化效率，同时高速氮气层流除去了大部分盐类，避免了盐类在质谱接口处的重结晶，并且喷雾与质谱进样口垂直设置，使得大部分基质、盐及不带电的离子不进入质谱口，大大降低了背景干扰。使用这一技术，首次发现了FAD和葡萄糖形成的两种结构不同的中间体，并证明了该中间体的形成是葡萄糖脱氢和FAD还原的重要环节。还结合同位素标记、光谱实验等手段验证了FAD还原所需的氢离子供体来自于酶，并解释了该反应过程的机理。最后利用MF-EESI对葡萄糖氧化反应进行了在线监测。该工作为复杂酶催化体系的反应研究提供了潜在有利工具。 （二） 喷雾介导等离子体离子源的构建及应用 常压质谱由于能够快速直接获取分子的结构信息，是研究分子的有效工具。然而在常压质谱技术中，电喷雾和大气压化学电离两大类技术分别用于分析极性分子和低极性小分子，并且所检测的分子量范围也存在差异，目前为止尚未出现兼具两者优势的离子化技术。基于此，我们设计了一种喷雾介导等离子体离子源（SDP），打破原有的技术限制，实现了单一离子源，通过适当调节即可完成“软”和“硬”两种电离方式，为检测不同极性和分子量的分子提供了有力工具。和传统电喷雾技术相比，我们通过使用这种离子源，不仅可以得到了完整的分子离子峰和它的碎片信号，还在高质量范围中得到了由分子弱相互作用形成的团簇的信号。该技术兼具电喷雾和大气压化学电离的检测特性，可以对不同极性不同大小的分子进行较为全面的检测，并也可以成为研究分子弱相互作用的有力工具，对有机合成、生化、医药和临床诊断有重要意义。 （三） 辅助放电式喷雾等离子体离子源的设计及其在反应在线监测中的应用 芳香基团的碳-碳键耦合反应在复杂有机分子的合成中占有重要地位，然而其较大的极性差异给同一体系内多种分子的同时离子化研究带来了挑战。基于此，本工作构建了一种基于导线辅助的快速自动抽提式喷雾离子源——辅助放电式喷雾等离子体离子源，通过铂丝位置的调整获得了以甲醇等低电导率样品为介导的低温等离子体（LTP）。工作中首先使用该装置检测了多种不同极性和分子量的物质，证明了这种离子化方式的普适性。继而，结合文丘里喷雾的自吸作用，将该离子源用于不同极性的反应体系研究。以氯苯和苯基硼酸为反应物的铃木-宫浦反应为例，我们发现该离子源中的铂丝会和中间体中的钯产生置换反应并产生相应的信号。通过跟踪铂代信号的强度，确定了该反应中控制速率的关键步骤，并结合文献再现了反应中催化剂所形成的中间体。该工作为多极性复杂体系反应的研究提供了潜在有力工具。

Mass spectrometry (MS) is one of the most powerful techniques to obtain molecular information and it can be used to characterize intermediates due to the advent of ionization methods such as electrospray ionization (ESI). Ambient MS techniques have emerged for quick data acquisition without sample pre-treatment, thereby facilitating reaction monitoring and mechanistic examinations. Here, in order to meet the increasing demands for analysis of numerous kinds of samples, three prototypes of ambient ion sources were developed and for applications on mechanism studies: 1. FAD roles in glucose catalytic oxidation studied by multiphase flow of extractive electrospray ionization mass spectrometry The role of the coenzyme flavin adenine dinucleotide (FAD) in the catalytic oxidation of glucose was elucidated by MS using a new extraction and ionization method of extractive electrospray ionization (MF-EESI). By a multiphase flow of liquid–gas, extractive electrospray ionization was achieved, and this technique decreased the salt-matrix interference effectively, avoided salt crystallizations at the capillary tip and increased ionization efficiency by a concentric-sprayed solvent. Notably, two intermediate complexes of FAD–glucose have been observed and differentiated for the first time using MF-EESI. These intermediate complexes were demonstrated to be responsible for the hydride abstraction from glucose, as well as the cyclic coenzyme conversion of FAD during glucose oxidation. Online monitoring was also employed in MF-EESI, thereby providing a potential and informative tool to scrutinize enzymatic catalytic reactions. 2. Fabrication and application of spray-dependent plasma Ambient mass spectrometry can be effective for molecular studies rapidly and directly. While there still seems to be a gap between two major groups of ESI and APCI-related techniques, for detection of moderately polar to polar, and low-polar to non-polar molecules in relative low mass range, respectively. Here, an extensively applicable “soft” and “hard” ionization method, spray-dependent plasma mass spectrometry, was established for detecting various molecules with di-verse polarities or molecular weights. By SDP MS, both fragment ions and intact molecular ions can be obtained. Significantly, cluster ions of aggregates in high mass range formed by weak molecular interactions can also be well recorded, much softer than traditional ESI MS. By filling the gap between ESI-based and APCI-based ionization techniques, SDP MS would enhance MS performance for comprehensive molecule studies, and be extensive applicable in fields of organic synthesis, biological chemistry, medical chemistry and clinical diagnose. 3. Fabrication of wire-assisted spray-dependent plasma for reaction monitoring Aromatic carbon-carbon bond coupling reactions have recently emerged as exceedingly important methodologies for the preparation of complex organic molecules such as pharmaceuticals. To examine this kind of reactions, a new ion source of wire-assisted spray-dependent plasma was developed. With the help of the inner Pt wire, the low temperature plasma (LTP) can be ignited under mild conditions. With the help of self-pumping effect provided by Ventruri neubulizer, samples from the reaction system of Suzuki-Miyaura Reaction were well exctrated and ionized for real-time examniations. As demonstrated, Pt wire inside ion source would substitute the centre metal ion of the intermediate, and the changes can be tracked in real-time. Therefore, the mechanism was prelimiary deduced to show potentials for mechanism examinations on chemical reactions in multi-polar matrix.