Atmospheric Pressure Dark-Current Argon Discharge Ionization with Comparable Performance to Direct Analysis in Real Time Mass Spectrometry
Atmospheric Pressure Dark-Current Argon Discharge Ionization with Comparable Performance to Direct Analysis in Real Time Mass Spectrometry
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DOI：
10.5702/massspectrometry.a0075
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发表时间：
2019-10
影响因子：
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通讯作者：
K. Sekimoto;M. Sakakura;Hiroshi Hike;Takatomo Kawamukai;Teruhisa Shiota;M. Takayama
中科院分区：
文献类型：
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作者：
K. Sekimoto;M. Sakakura;Hiroshi Hike;Takatomo Kawamukai;Teruhisa Shiota;M. Takayama
在此，描述了通过在环境空气中将氩气流与针电极组合而产生的暗电流放电状态，其具有与常规的真实的时间（DART）中的氦直接分析相当的电离效率和机制，而不需要掺杂剂和DART辉光放电。利用该方法，在暗电流氩气放电中，对α-氨基酸等极性化合物进行了电离，电离过程包括质子化（去质子化）、分子阴离子形成、裂解、质子化（去质子化）和氧的附着、质子化（去质子化）和氢的损失以及负离子的附着。相反，非极性化合物（例如，正构烷烃）通过氢化物提取和氧化被检测为正离子。观察到的主要背景离子为H3 O+（H2O）n、O2·+、O2·−（H2O）n和CO 3·−。这些结果表明，本发明的暗电流放电有效地产生共振态氩，其内能为14.2eV，高于公知的亚稳态（11.6eV）的内能。因此，有人建议，电离反应发生在那里可以归因于潘宁电离大气中的H2O和O2的共振态氩，类似于氦DART。
Herein, a dark-current discharge state created by combining argon flow with a needle electrode in ambient air is described that has an ionization efficiency and mechanism comparable to those of conventional helium direct analysis in real time (DART), without requiring dopants and DART glow discharge. Using this method, polar compounds such as α-amino acids were ionized in the dark-current argon discharge via (de)protonation, molecular anion formation, fragmentation, (de)protonation with the attachment of oxygen, deprotonation with hydrogen loss and negative ion attachment. In contrast, nonpolar compounds (e.g., n-alkanes) were detected as positive ions via hydride abstraction and oxidation. Major background ions observed were H3O+(H2O)n, O2·+, O2·−(H2O)n and CO3·−. These results indicate that the present dark-current discharge efficiently generates resonance-state argon with an internal energy of ∼14.2 eV, higher than that of the well-known metastable state (∼11.6 eV). It is therefore suggested that ionization reactions occurring there can be attributed to the Penning ionization of atmospheric H2O and O2 by resonance-state argon, analogous to helium DART.