Characteristics of Low-Temperature Plasma Ionization for Ambient Mass Spectrometry Compared to Electrospray Ionization and Atmospheric Pressure Chemical Ionization
Characteristics of Low-Temperature Plasma Ionization for Ambient Mass Spectrometry Compared to Electrospray Ionization and Atmospheric Pressure Chemical Ionization
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DOI：
10.1021/ac302287x
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发表时间：
2012-12-18
影响因子：
7.4
通讯作者：
Engelhard, Carsten
中科院分区：
文献类型：
--
作者：
Albert, Anastasia;Engelhard, Carsten
环境解吸/电离质谱法（ADI-MS）是一种有吸引力的直接分析方法，应用于国土安全、法医和人类健康。例如，低温等离子体探针（LTP）电离被成功地用于直接检测目标上的爆炸物、药物和杀虫剂等。尽管该领域受到了极大的关注，但与质谱中使用的传统电离源相比，很少有人尝试根据电离特性和性能对环境电离技术进行分类。本研究利用LTP-Orbitrap-MS测定了大量化合物族的相对电离效率（RIEs），并与电喷雾电离质谱法（ESI-MS）和大气压化学电离质谱法（APCI-MS）进行了比较。为了确保结果的可比性，对所有方法中使用的一种参比化合物进行了归一化。通常，LTP分析物电离通过质子化/去质子化（例如，4-乙酰氨基酚）被观察到；在某些情况下（例如，苊）自由基形成。用LTP成功地电离了胺、酰胺和醛。与传统方法相比，LTP的一个优点是可以成功地电离多环芳烃和亚胺。在这里，所研究的模型化合物既不能用APCI也不能用ESI检测到。LTP是一种相对较软的电离方法，因为模型化合物几乎没有碎裂。它被认为是在相对宽的极性范围内电离低分子量化合物的一种有吸引力的方法。
Ambient desorption/ionization mass spectrometry (ADI-MS) is an attractive method for direct analysis with applications in homeland security, forensics, and human health. For example, low-temperature plasma probe (LTP) ionization was successfully used to detect, e.g., explosives, drugs, and pesticides directly on the target. Despite the fact that the field is gaining significant attention, few attempts have been made to classify ambient ionization techniques based on their ionization characteristics and performance compared to conventional ionization sources used in mass spectrometry. In the present study, relative ionization efficiencies (RIEs) for a large group of compound families were determined with LTP-Orbitrap-MS and compared to those obtained with electrospray ionization mass spectrometry (ESI-MS) and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). RIEs were normalized against one reference compound used across all methods to ensure comparability of the results. Typically, LTP analyte ionization through protonation/deprotonation (e.g., 4-acetamidophenol) was observed; in some cases (e.g., acenaphthene) radicals were formed. Amines, amides, and aldehydes were ionized successfully with LTP. A benefit of LTP over conventional methods is the possibility to successfully ionize PAHs and imides. Here, the studied model compounds could be detected by neither APCI nor ESI. LTP is a relatively soft ionization method because little fragmentation of model compounds was observed. It is considered to be an attractive method for the ionization of low molecular weight compounds over a relatively wide polarity range.