In situ measurements of atmospheric nitrous acid by chemical ionization mass spectrometry using chloride ion transfer reactions.
In situ measurements of atmospheric nitrous acid by chemical ionization mass spectrometry using chloride ion transfer reactions.
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DOI：
10.1021/ac901117b
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发表时间：
2009-09
影响因子：
7.4
通讯作者：
J. Hirokawa;Takehiro Kato;F. Mafuné
中科院分区：
文献类型：
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作者：
J. Hirokawa;Takehiro Kato;F. Mafuné
近年来，化学电离质谱仪(CIMS)被广泛应用于大气痕量组分的现场测量。本文提出了以SO(2)-Cl(-)为试剂离子发生氯离子转移反应的新的化学电离方案，并讨论了该技术在大气中亚硝酸(HONO)检测中的适用性。实验室研究发现，检测灵敏度依赖于注入离子源区的SO2流量和化学电离区内的压力，这表明化学电离反应是可逆的。检测灵敏度可以用正向速率和反向速率来很好地描述。目前的检测极限估计为1分钟的积分时间的万亿分之60(PPTV)。CIMS仪器的改进将能够测量白天的HONO水平，可能低于50pptv。此外，基于从头计算的热力学考虑，讨论了干扰的可能性，并从实验上量化了采样伪影的影响。
Recently, chemical ionization mass spectrometry (CIMS) has been widely applied to the in situ measurements of atmospheric trace species. In this article, we propose a new chemical ionization scheme using a chloride ion transfer reaction from SO(2)Cl(-) as the reagent ion and discuss the applicability of this technique to the detection of nitrous acid (HONO) in the atmosphere. From laboratory investigations, the detection sensitivity was found to depend on the flow rate of SO(2) introduced into the ion source region and the pressure inside the chemical ionization region, which suggests that the chemical ionization reaction is reversible. The detection sensitivity was well described in terms of the forward and backward rates. The present limit of detection is estimated to be 60 parts per trillion by volume (pptv) for an integration time of 1 min. Improvement of the CIMS instrument would enable the measurements of the daytime level of HONO, which might be less than 50 pptv. In addition, the possibility of the interference is discussed from thermodynamic considerations based on ab initio calculations, and the effects of the sampling artifacts are experimentally quantified.