Space Charge Induced Dissociation Due to Extended Ion Accumulation Preceding Cyclic Ion Mobility Separation

Area of Science:

• Analytical Chemistry
• Physical Chemistry

Background:

• Cyclic ion mobility spectrometry (cIMS) enables high-resolution separation of small molecule isomers through multipass analysis.
• Analyte ion stability is a critical limitation for achieving optimal resolution in cIMS.
• Previous studies indicated fragmentation of dexamethasone and betamethasone during long multipass separations.

Purpose of the Study:

• To investigate the causes of analyte ion loss in cIMS.
• To differentiate between ion loss due to long exposure times and space charge effects.
• To understand the impact of ion accumulation on analyte stability in cIMS.

Main Methods:

• Utilized cyclic ion mobility spectrometry (cIMS) for isomer separation.
• Varied pre-cIMS ion accumulation times to assess space charge effects.
• Analyzed ion fragmentation patterns in relation to ion density and accumulation duration.

Main Results:

• Analyte loss in cIMS is predominantly linked to space charge effects caused by high ion densities during accumulation.
• Ion fragmentation is exacerbated by prolonged ion accumulation prior to cIMS injection.
• The duration of exposure to the cIMS region is a less significant factor in analyte loss compared to pre-accumulation effects.

Conclusions:

• Space charge effects during ion accumulation are a primary driver of analyte fragmentation in cIMS.
• Optimizing ion accumulation protocols is crucial for enhancing analyte stability and improving cIMS resolution.
• Regulating ion density prior to IMS injection is essential for successful high-resolution separations.