U.S. Department of Energy

Pacific Northwest National Laboratory

Improving Ion Mobility Measurement Sensitivity by Utilizing Helium in an Ion Funnel Trap

Ion mobility spectrometry (IMS) is a gas phase separation technique in which ions are distinguished according to their collision cross sections. Ion packets are pulsed into a drift cell that contains a buffer gas (usually He or N2) and pulled by a uniform weak electric field. Traditionally, ion traps that precede drift cell utilize the same buffer gas composition as the drift cell. In this work we show that introducing helium into the trap while operating the drift cell with nitrogen further improves the sensitivity of the platform, in some cases by more than an order of magnitude. This improvement is attributed to the faster ejection of ions from the trap.

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