Lippmann Martin, Hitzemann Moritz, Nitschke Alexander, Zimmermann Stefan
Department of Sensors and Measurement Technology, Institute of Electrical Engineering and Measurement Technology, Leibniz Universität Hannover, Appelstr. 9A, Hannover 30167, Germany.
Anal Chem. 2025 Apr 22;97(15):8609-8616. doi: 10.1021/acs.analchem.5c01027. Epub 2025 Apr 10.
Ion mobility spectrometers are extremely sensitive analytical instruments, consisting of an ionization region and a drift region, usually separated by an ion shutter. Highest sensitivity is reached with field-switching ion shutters, as ions are accumulated in the ionization region while the ion shutter is closed, which defines the reaction time in the ionization region. This study investigates the effect of repetition rate and reaction time on ion formation and detection limits. The results reveal that increasing the ionization source intensity and reaction time increases the signal-to-noise ratio even though less spectra can be averaged in a given overall measuring time. It is shown that the formation of protonated monomers and proton-bound dimers is considerably slower than the formation of reactant ions, highlighting the impact of reaction time on signal-to-noise ratio. At maximum ionization source intensity and optimal reaction times for the protonated monomers and proton-bound dimers of 1-butanol, limits of detection of 1.9 ppt and 110 ppt could be reached. For the protonated monomers and proton-bound dimers of 2-butanone, the limits of detection are 1.3 ppt and 57 ppt. The given limits of detection refer to an averaging time of 1 s. Although the optimal reaction times differ for different protonated monomers and proton-bound dimers, a reaction time of 40 ms was identified as a good compromise. These findings provide valuable insights into how the reaction time, and thus repetition rate and cycle time, impacts the detection limits of ion mobility spectrometers equipped with field-switching ion shutters.
离子迁移谱仪是极其灵敏的分析仪器，由一个电离区和一个漂移区组成，通常由一个离子快门隔开。使用场切换离子快门可达到最高灵敏度，因为在离子快门关闭时离子在电离区积累，这就确定了电离区的反应时间。本研究调查了重复率和反应时间对离子形成及检测限的影响。结果表明，即使在给定的总测量时间内可平均的光谱较少，但增加电离源强度和反应时间会提高信噪比。结果表明，质子化单体和质子键合二聚体的形成比反应物离子的形成要慢得多，这突出了反应时间对信噪比的影响。在1-丁醇的质子化单体和质子键合二聚体的最大电离源强度和最佳反应时间下，检测限可达到1.9 ppt和110 ppt。对于2-丁酮的质子化单体和质子键合二聚体，检测限分别为1.3 ppt和57 ppt。给定的检测限指的是1秒的平均时间。尽管不同质子化单体和质子键合二聚体的最佳反应时间不同，但40毫秒的反应时间被认为是一个不错的折衷方案。这些发现为反应时间以及重复率和循环时间如何影响配备场切换离子快门的离子迁移谱仪的检测限提供了有价值的见解。
