Determination of Gas-Phase Ion Mobility Coefficients Using Voltage Sweep Multiplexing

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Spectrometry

Background:

• Standard drift tube ion mobility spectrometry (IMS) experiments utilize less than 1% of ions, leading to low detector signals and duty cycles.
• The increasing demand for higher resolution separations and lower duty cycles in IMS, coupled with faster detector sampling rates, necessitates improved experimental methods.
• Timing incompatibilities exist between standard IMS and certain mass spectrometers (e.g., ion traps), hindering hyphenated techniques like ion mobility-mass spectrometry (IM-MS).

Purpose of the Study:

• To develop a novel ion multiplexing technique for ion mobility spectrometry to enhance ion utilization efficiency.
• To address the limitations of standard IMS experiments, including low duty cycles and incompatibility with certain mass spectrometers.
• To present the theory and initial results of a new method called voltage sweep multiplexing (VSM).

Main Methods:

• Implementation of a dual-gate ion mobility spectrometer for ion multiplexing.
• Development and application of voltage sweep multiplexing (VSM), a novel technique involving dynamic electric field changes within the drift cell.
• Simultaneous opening of ion gates at a constant frequency during the voltage sweep.

Main Results:

• Voltage sweep multiplexing (VSM) significantly increases ion utilization efficiency compared to standard IMS.
• VSM generates a measurement signal compatible with low sampling rates, overcoming detector limitations.
• Proof-of-concept measurements validate the fundamental theory of VSM, with key variables discussed and verified against traditional methods.

Conclusions:

• Voltage sweep multiplexing (VSM) offers a viable solution to enhance ion utilization in drift tube IMS.
• This technique improves compatibility with various mass spectrometers, broadening the applicability of ion mobility-mass spectrometry (IM-MS).
• VSM represents a significant advancement in ion mobility spectrometry, enabling more efficient and versatile measurements.