Ultralong transients enhance sensitivity and resolution in Orbitrap-based single-ion mass spectrometry

Orbitrap-based charge detection mass spectrometry utilizes single-molecule sensitivity to enable mass analysis of even highly heterogeneous, high-mass macromolecular assemblies. For contemporary Orbitrap instruments, the accessible ion detection (recording) times are maximally ~1–2 s. Here by modifying a data acquisition method on an Orbitrap ultrahigh mass range mass spectrometer, we trapped and monitored individual (single) ions for up to 25 s, resulting in a corresponding and huge improvement in signal-to-noise ratio (×5 compared with 1 s), mass resolution (×25) and accuracy in charge and mass determination of Orbitrap-based charge detection mass spectrometry. Implementation of ultralong transients on an Orbitrap mass spectrometer improves mass resolution, sensitivity and accuracy of charge determination in the analysis of large macromolecular ions.