Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Leibniz University Hannover, Appelstr. 9A, 30167, Hannover, Germany.
Anal Bioanal Chem. 2021 Feb;413(4):1009-1016. doi: 10.1007/s00216-020-03059-9. Epub 2020 Nov 21.
Ion mobility spectrometers can detect gaseous compounds at atmospheric pressure in the range of parts per trillion within a second. Due to their fast response times, high sensitivity, and limited instrumental effort, they are used in a variety of applications, especially as mobile or hand-held devices. However, most real-life samples are gas mixtures, which can pose a challenge for IMS with atmospheric pressure chemical ionization mainly due to competing gas-phase ionization processes. Therefore, we present a miniaturized drift tube IMS coupled to a compact gas chromatograph for pre-separation, built of seven bundled standard GC columns (Rtx-Volatiles, Restek GmbH) with 250 μm ID and 1.07 m in length. Such pre-separation significantly reduces chemical cross sensitivities caused by competing gas-phase ionization processes and adds orthogonality. Our miniaturized GC-IMS system is characterized with alcohols, halocarbons, and ketones as model substances, reaching detection limits down to 70 ppt with IMS averaging times of just 125 ms. It separates test mixtures of ketones and halocarbons within 180 s and 50 s, respectively. The IMS has a short drift length of 40.6 mm and reaches a high resolving power of R = 68. Graphical abstract.
离子迁移谱仪能够在大气压下每秒检测到万亿分之几部分的气态化合物。由于其响应时间快、灵敏度高、仪器消耗低，因此被应用于各种领域，尤其是作为移动或手持式设备。然而，大多数实际样品都是气体混合物，这对大气压化学电离的 IMS 构成了挑战，主要是由于竞争的气相电离过程。因此，我们提出了一种小型化的漂移管 IMS，与紧凑的气相色谱仪联用，用于预分离，该气相色谱仪由七个捆绑的标准 GC 柱（Rtx-Volatiles，Restek GmbH）组成，内径为 250μm，长度为 1.07m。这种预分离显著降低了竞争气相电离过程引起的化学交叉灵敏度，并增加了正交性。我们的小型化 GC-IMS 系统以醇类、卤代烃和酮类作为模型物质进行了表征，平均 IMS 时间仅为 125ms 时，检测限可低至 70ppt。它能够在 180s 和 50s 内分别分离出酮类和卤代烃的测试混合物。IMS 的漂移长度短，为 40.6mm，达到了 68 的高分辨率。
