Ion Trap with Narrow Aperture Detection Electrodes for Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Abstract

Abstract. The current paradigm in ion trap (cell) design for Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is the ion detection with wide aperture detection electrodes. Specifically, excitation and detection electrodes are typically 90°wide and positioned radially at a similar distance from the ICR cell axis. Here, we demonstrate that ion detection with narrow aperture detection electrodes (NADEL) positioned radially inward of the cell's axis is feasible and advantageous for FT-ICR MS. We describe design details and performance characteristics of a 10 T FT-ICR MS equipped with a NADEL ICR cell having a pair of narrow aperture (flat) detection electrodes and a pair of standard 90°excitation electrodes. Despite a smaller surface area of the detection electrodes, the sensitivity of the NADEL ICR cell is not reduced attributable to improved excite field distribution, reduced capacitance of the detection electrodes, and their closer positioning to the orbits of excited ions. The performance characteristics of the NADEL ICR cell are comparable with the state-of-the-art FT-ICR MS implementations for small molecule, peptide, protein, and petroleomics analyses. In addition, the NADEL ICR cell's design improves the flexibility of ICR cells and facilitates implementation of advanced capabilities (e.g., quadrupolar ion detection for improved mainstream applications). It also creates an intriguing opportunity for addressing the major bottleneck in FTMS-increasing its throughput via simultaneous acquisition of multiple transients or via generation of periodic non-sinusoidal transient signals.

Ion Coalescence in Fourier Transform Mass Spectrometry: Should We Worry about This in Shotgun Proteomics?

“…Apart from the speed, the other key factor in achieving such a performance is the ability of the FT mass analyzers to measure masses of atomic 10 and/or biomolecular ions 11,12 at sub parts per million levels of mass accuracy and to resolve isobaric ions with mass differences lower than and comparable to the mass of an electron. [13][14][15] The dynamic range of a mass analyzer is another important factor, affecting its performance in shotgun proteome analysis. For example, the dynamic range of the Orbitrap FTMS for proteomics applications, which requires a high resolving power and mass-measurement accuracy, was reported to be up to 10 4 .…”

Parallel detection in a single ICR cell: Spectral averaging and improved S/N without increased acquisition time

“…As with most ICR cells, decreased S/N at higher excitation amplitude could be due to the reduced trapping electric potential harmonicity and excitation electric field homogeneity and loss of ions and/or phase coherence at larger radius. [19] No significant difference in the S/N was observed among the 4 detection electrode pairs.…”

Producing absorption mode Fourier transform ion cyclotron resonance mass spectra with non‐quadratic phase correction functions

“…An ICR cell with narrow aperture detection electrodes (NADEL), based on the open‐ended cylindrical ICR cell (Ultra Cell, Thermo Scientific), was used. The design of this cell has previously been described in detail . Experimental data were acquired in two different ion detection regimes by adjusting the tuning of the DC offset voltages applied to the excitation electrodes of the NADEL ICR cell .…”