Influence of ionization volume and sample gas flow rate on separation power in gas chromatography-ion mobility spectrometry

• Published in: Journal of Chromatography A Vol. 1713; p. 464506
• Main Authors: Kobelt, Tim, Lippmann, Martin, Wuttke, Jannik, Wessel, Hanno, Zimmermann, Stefan
• Format: Journal Article
• Language: English
• Published: Netherlands 04.01.2024
• Subjects: Ionization volume; Peak broadening; GC-IMS; Effective detector volume
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2023.464506

In this work, the influence of the sample gas flow rate and the ionization region volume of an ion mobility spectrometer (IMS) used as a detector in gas chromatography (GC) on GC-IMS peak shape has been investigated. Therefore, a drift tube IMS with a field-switching ion shutter, a defined ionization region volume and an ultra-violet radiation source was used. To identify the influence of the sample gas flow rate entering the ionization region (equals the GC carrier gas flow rate if no further make-up gas is used) and the ionization region volume on peak broadening and signal intensity, different sample volumes as they would elute from a GC were tested at a variety of sample gas flow rates at a given ionization region volume. The results clearly show that for low sample gas flow rates a depletion of sample molecules in the ionization region leads to a significant decrease in effective detector volume but also to reduced signal intensities. Therefore, for optimal performance of a GC-IMS, the optimal operating point of the GC should match the flow range, where the IMS provides the best compromise between signal-to-noise ratio and peak broadening.