Gaik Urszula, Sillanpää Mika, Witkiewicz Zygfryd, Puton Jarosław
Institute of Chemistry, Military University of Technology, Kaliskiego 2, 00-908, Warsaw, Poland.
School of Engineering Science, Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130, Mikkeli, Finland.
Anal Bioanal Chem. 2017 May;409(12):3223-3231. doi: 10.1007/s00216-017-0265-2. Epub 2017 Mar 3.
Limits of detection (LODs) in ion mobility spectrometry (IMS) strictly depend on ionization of the analyte. Especially challenging is ionization of compounds with relatively low proton affinity (PA) such as aromatic compounds. To change the course of ion-molecule reactions and enhance the performance of the IMS spectrometer, substances called dopants are introduced into the carrier gas. In this work, we present the results of studies of detection using nitrogen oxides (NO) dopants. Three aromatic compounds, benzene, toluene, toluene diisocyanate and, for comparison, two compounds with high PA, dimethyl methylphosphonate (DMMP) and triethyl phosphate (TEP), were selected as analytes. The influence of water vapour on these analyses was also studied. Experiments were carried out with a generator of gas mixtures that allowed for the simultaneous introduction of three substances into the carrier gas. The experiments showed that the use of NO dopants significantly decreases LODs for aromatic compounds and does not affect the detection of compounds with high PA. The water vapour significantly disturbs the detection of aromatic compounds; however, doping with NO allows to reduce the effect of humidity. Graphical Abstract Two possible ionization mechanisms of aromatic compounds in ion mobility spectrometry: proton transfer reaction and adduct formation.
离子迁移谱（IMS）中的检测限严格取决于分析物的电离。对于质子亲和力（PA）相对较低的化合物（如芳香族化合物）的电离尤其具有挑战性。为了改变离子 - 分子反应的进程并提高IMS光谱仪的性能，将称为掺杂剂的物质引入载气中。在这项工作中，我们展示了使用氮氧化物（NO）掺杂剂进行检测的研究结果。选择了三种芳香族化合物，苯、甲苯、甲苯二异氰酸酯，以及作为对比的两种高PA化合物，甲基膦酸二甲酯（DMMP）和磷酸三乙酯（TEP）作为分析物。还研究了水蒸气对这些分析的影响。实验使用了一种气体混合物发生器，该发生器允许将三种物质同时引入载气中。实验表明，使用NO掺杂剂可显著降低芳香族化合物的检测限，并且不影响高PA化合物的检测。水蒸气会显著干扰芳香族化合物的检测；然而，用NO掺杂可以降低湿度的影响。图形摘要 离子迁移谱中芳香族化合物的两种可能电离机制：质子转移反应和加合物形成。
