Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran.
TOF Tech. Pars Company, Isfahan Science & Technology Town, Isfahan, Iran.
J Chromatogr A. 2020 Dec 20;1634:461676. doi: 10.1016/j.chroma.2020.461676. Epub 2020 Nov 12.
A rapid and simple method is proposed for detection of elemental mercury (Hg) vapor by ion mobility spectrometry (IMS). Negative corona discharge (CD) as the ionization source and chloroform as the dopant gas were used to produce Cl reactant ion. A mass spectrum of the product ions confirmed that the mechanism of ionization is based on Cl anion attachment to Hg and formation of HgCl ion. It was found that the optimum drift gas temperature for Hg detection was about 160 °C and the drift gas flow rate should be minimized and just sufficient to clear contaminants and carry-over from the drift cell. The drift time of the HgCl peak relative to that of the Cl peak at 160 °C is 1.52 ms corresponding to the reduced mobility of 1.90 cm/Vs. Because many volatile organic compounds (VOCs) such as alcohols, amines, aldehydes, ketones, and alkanes are not ionized in the negative mode of CD-IMS, these compounds do not interfere with the detection of Hg. Mercaptans peaks also did not show any interference with the Hg signal. Hence, the method is highly selective for detection of Hg in natural gas containing sulfur compounds. The detection limit of Hg obtained by the proposed method was 0.07 mg/m. The method was successfully verified in determination of the mercury vapor content of a fluorescent lamp, as a real sample.
提出了一种快速、简单的方法，通过离子迁移谱（IMS）检测元素汞（Hg）蒸气。采用负电晕放电（CD）作为电离源，氯仿作为掺杂气体，产生 Cl 反应离子。产物离子的质谱证实，电离机制基于 Cl 阴离子与 Hg 的附着以及 HgCl 离子的形成。结果表明，Hg 检测的最佳漂移气体温度约为 160°C，漂移气体流量应最小化，只需足以清除漂移室中的污染物和携带物。在 160°C 时，HgCl 峰的漂移时间相对于 Cl 峰的漂移时间为 1.52ms，对应的迁移率为 1.90cm/Vs。由于许多挥发性有机化合物（VOCs），如醇、胺、醛、酮和烷烃，在 CD-IMS 的负模式下不会被电离，因此这些化合物不会干扰 Hg 的检测。巯基化合物的峰也没有对 Hg 信号产生任何干扰。因此，该方法对含硫化合物的天然气中 Hg 的检测具有高度选择性。该方法在荧光灯中汞蒸气含量的测定中得到了验证，是一种实际样品。
