Parallel accumulation for 100% duty cycle trapped ion mobility-mass spectrometry

- TIMS-TOF instrument featuring a new ion accumulation trap upstream of the mobility analyzer.
- TIMS resolving power of ∼60 at 100% duty cycle.
- Enhancement of the mass spectral peak intensities by an average factor of ∼80.

A new trapped ion mobility spectrometry (TIMS) apparatus has been developed and evaluated. Building on the original prototype design, the new spectrometer includes an upstream “ion accumulation trap”. Inclusion of the new trap allows for storage of a population of ions during the analysis of a previously stored population of ions. By accumulating and analyzing ions in parallel, rather than in series, a duty cycle of 100% can be achieved. The new design retains the flexibility of the original design-the ability to exchange mobility range, resolution, and speed/duty cycle-while in all instances, maintaining superior ion utilization efficiency. When operating at 100% duty cycle, the spectrometer is shown to trap a broad range of ions (m/z 622-2722) with an average trapping efficiency of ∼70%. Trapping efficiency was found to be constant over a range of accumulation/analysis times from 20 up to 85 ms where an average resolving power of 60 was achieved. Compared to transmission mode (MS-only) operation, the combination of high mobility resolving power, high ion utilization efficiency, and relatively fast scan times achieved with TIMS is shown to result in an improvement in mass spectral peak intensities of more than an order of magnitude.

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