Buffer gas modifiers effect resolution in ion mobility spectrometry through selective ion-molecule clustering...

Area of Science:

• Analytical Chemistry
• Physical Chemistry

Background:

• Ion mobility spectrometry (IMS) typically sees reduced ion mobilities when polar modifiers form ion-modifier clusters in the buffer gas.
• Understanding how modifiers affect ion mobility is crucial for optimizing IMS analyses.

Purpose of the Study:

• To investigate the effect of novel buffer gas modifiers on ion mobility.
• To determine if specific analyte structures, like intramolecular bridges, influence mobility changes in the presence of modifiers.
• To assess the utility of modifier-induced mobility shifts for separating overlapping ions in IMS.

Main Methods:

• Utilized electrospray ionization ion mobility spectrometry (IMS) coupled to quadrupole mass spectrometry.
• Tested ethyl lactate, nitrobenzene, 2-butanol, and tetrahydrofuran-2-carbonitrile as buffer gas modifiers.
• Analyzed the mobility of various compounds, including diamines and small molecules like ethanolamine.

Main Results:

• Ion mobilities of diamines (arginine, histidine, lysine, atenolol) were minimally affected by modifiers due to intramolecular bridges hindering clustering.
• Smaller analytes, like ethanolamine, showed significant mobility reductions (up to 61%) with modifier addition.
• Observed selective mobility alterations enabled separation of previously overlapping ions (e.g., isoleucine/lysine, arginine/phenylalanine).

Conclusions:

• Introduction of buffer gas modifiers in IMS can selectively modulate analyte mobilities.
• This selective alteration aids in compound identification and resolves overlapping peaks.
• The structural features of analytes, particularly intramolecular bridges, dictate their response to buffer gas modifiers.