苯系物的色谱光电离迁移谱两维分辨检测方法研究

Aromatic compounds separation and detection by tandem gas chromatography and photoionization ion mobility spectrometry

针对离子迁移谱难分辨迁移率相近或相同的有机物,开展了气相色谱-紫外光电离-离子迁移谱联用技术的研究。通过测量不同色谱柱温和氮载气流量条件下苯的色谱和迁移谱,对实验参数进行了优化。并对苯、甲苯,以及邻、间、对-二甲苯等五种苯系物混合物进行了测量,获得了混合样品的色谱保留时间、迁移谱离子迁移时间与离子信号强度的三维谱图。结果表明,同分异构体邻、间、对-二甲苯的迁移率非常接近,单一的紫外光电离-离子迁移谱无法对它们进行分辨,通过色谱-迁移谱技术的联用,则可以实现苯、甲苯,以及邻、间、对-二甲苯混合物的有效分辨。证明所建立的气相色谱-紫外光电离-离子迁移谱技术具有良好的分辨检测能力。

Ion mobility spectrometry （IMS） is difficult to identify some organic compounds with closed reduced mobility values, such as the isomeric compounds of xylene. A tandem analytical technique, UV photoionization ion mobility spectrometry （UV-IMS） coupled with a packed column gas chromatography （GC）, GC-UV-IMS, was developed for the efficient separation and detection of aromatics compounds. The gas chromatograms and ion mobility spectra were measured at different column temperatures and the flows of nitrogen carrier gas in order to obtain optimized experimental parameters. The gaseous mixture of benzene, toluene, o-xylene, m-xylene and p-xylene was detected with a homemade GC-UV-IMS apparatus. The results show that three isomeric compounds o-xylene, m-xylene and p-xylene can not be distinguished when only using the UV photoionization IMS. However, two dimensional gas chromatogram-ion mobility spectrum can greatly enhance resolution of these organic compounds on the basis of their retention time and drift time. This demonstrates that the established GC-UV-IMS has a good ability to discriminate and detect trace volatile organic compounds.