Transversal Modulation Ion Mobility Spectrometry (TM-IMS), a new mobility filter overcoming turbulence related limitations.

The analysis of ions according to their mobility is a technique that is attracting increasing interest. The new technology presented here, which we have termed Transversal Modulation Ion Mobility Spectrometry (TM-IMS), utilizes only electric fields, operates at atmospheric pressure, produces a continuous output of mobility selected ions (according to their true mobility and not to nonlinear effects), and has a very accessible inlet and outlet. These features would make it an ideal choice for tandem IMS-MS analysis in combination with most commercial Atmospheric Pressure Interface MS (API-MS) systems. We modeled and evaluated two different TM-IMS configurations (TM-IMS, and multistage TM-IMS), and we concluded that the most promising configuration would be a two-stage TM-IMS. We developed and tested a TM-IMS, and the measured resolving power is R = 55. The TM-IMS behaves similarly to the planar Differential Mobility Analyzer, but the TM-IMS utilizes only electric fields, and no fragile flow with high Reynolds numbers is required. We tested the robustness of the TM-IMS, which proves to be a very robust and reliable analyzer: the required voltage accuracy is 5 V in 10 kV, and the mechanical precision is 1 mm in 5 cm.