Lewis Cris L, Moser Mathew A, Dale Don E, Hang Wei, Hassell Christian, King Fred L, Majidi Vahid
Chemistry Division, Los Alamos National Laboratory, New Mexico 87545, USA.
Anal Chem. 2003 May 1;75(9):1983-96. doi: 10.1021/ac026242u.
A millisecond pulsed glow discharge is used as a versatile ion source for time-gated generation of elemental, structural, and molecular ions. The utility of this ion source for comprehensive chemical analysis of a series of aromatic and halogenated hydrocarbons is illustrated in this manuscript. To highlight the analytical utility of this transient ion source, it was connected to a gas chromatograph for the mass spectrometric determination of mixtures containing benzene, toluene, o-xylene, cymene, tert-butylbenzene, carbon tetrachloride, chloroform, chlorobenzene, tetrachlorethane, and dichlorobenzene. Explicit chemical analysis was accomplished by introducing the GC eluent into a pulsed glow discharge operating at a rate of 100 Hz with a 50% duty cycle. Using three independent digitizers for time-gated acquisition in three separate time regimes, nearly concurrent collection of elemental, structural, and molecular information was accomplished. In general, elemental information was obtained during the first 0.015 ms after the plasma onset; structural information, as ascertained from molecular fragmentation, was obtained during the plateau time regime when the plasma pulse is at a steady state, whereas molecular M(+) and MH(+) ions were obtained during the afterpeak time regime, that is, after the cessation of the plasma power pulse.
毫秒脉冲辉光放电用作一种通用离子源，用于时间门控产生元素离子、结构离子和分子离子。本文展示了该离子源在一系列芳烃和卤代烃综合化学分析中的应用。为突出这种瞬态离子源的分析效用，将其连接到气相色谱仪上，用于质谱测定含有苯、甲苯、邻二甲苯、异丙苯、叔丁基苯、四氯化碳、氯仿、氯苯、四氯乙烷和二氯苯的混合物。通过以100 Hz的频率、50%的占空比将气相色谱洗脱液引入脉冲辉光放电来完成明确的化学分析。使用三个独立的数字化仪在三个不同的时间区域进行时间门控采集，几乎同时收集了元素信息、结构信息和分子信息。一般来说，在等离子体开始后的最初0.015毫秒内获得元素信息；从分子碎片化确定的结构信息，在等离子体脉冲处于稳态的平稳时间区域内获得，而分子M(+)和MH(+)离子在余辉时间区域内获得，即在等离子体功率脉冲停止之后。
