Performance Evaluation of Constant Field and Traveling Wave-Based Structures for Lossless Ion Manipulations Devices Coupled to Mass Spectrometry.

The performances of three prototype structures for lossless ion manipulations IMS mass spectrometer (SLIM IMS-MS) are evaluated. The instrument was constructed by replacing the drift tube of an Agilent 6560 with either traveling wave (TW) or constant field (CF) based SLIM modules of nearly identical length. The TW-SLIM module contains a 79.4 cm straight path and a 10 m serpentine path. The evaluation of these systems enabled the direct determination of performance differences associated with the drift tube replacement by the SLIM devices. The evaluation included comparing the resolution, resolving power, transmitted mass range, and collisional cross-section (CCS) accuracy relative to its drift tube counterpart for each device/path. Results indicated that the 79.4 cm CF-SLIM displayed comparable performance to the drift tube while the 79.4 cm TW-SLIM path provided ∼25% higher resolution and resolving powers (R_p) (R_p = 67-90 for a range of singly charged analyte ions) compared to the drift tube. The 10 m path showed an increase of up to 300%. Synchronizing the introduction of ions from the ion funnel trap with the traveling waveform enabled the mitigation of mass discrimination during ion transfer into the TW-SLIM module, resulting in an m/z distribution similar to that of the drift tube. A comparison of CCS obtained with the drift tube and TW/CF-SLIM IMS shows good overall agreement (∼±1.5%) for most of the molecular classes investigated. The results presented here provide a normalized comparison between the separation methods, highlighting the advantages and areas for improvement in SLIM-based ion mobility devices.