Fig. 1: Instrumental setup, principal, and performance characterization of the ion cloud profiling technology.
From: High-resolution separation of bioisomers using ion cloud profiling
Schematics of a the miniature MS system used in this work and b its key components for isomer structural analysis. c Simulated ion trajectories for two isomeric ions characterized by reduced damping coefficients: \({b}^{{\prime} }\,\)= 0.0010 (blue) and 0.0012 (purple). Here, \({b}^{{\prime} }=2b/\varOmega m\), where \(\varOmega\) is the angular frequence of the RF field, m is ion mass, b is the damping coefficient of the ions. Insets, zoom-in plots of the ion trajectories at the beginning (1) and ejection (2) stages of the AC excitation. Isomeric ions are ejected sequentially according to their DCSs when their oscillation amplitudes exceed the trap geometry, r0, as indicated by the blue dashed lines. d Ion cloud profiling spectra of three biomolecules, lactose (m/z 365, CCS 177.6 Å2), phosphatidylcholine (PC) 18:1/16:0 (m/z 761, CCS 296.2 Å2), and an acetylated peptide (m/z 542, CCS 357.9 Å2), superimposed in one spectrum. The CCS values of lactose and peptide are measured by timsTOF (Bruker Daltonics, Bremen, Germany). The CCS value of phosphatidylcholine is taken from Groessl’s work42. The resolution here is defined as, \(R={V}_{{AC}}/\triangle {V}_{{AC}}\), where \({V}_{{AC}}\) and \(\triangle {V}_{{AC}}\) are the AC ejection amplitude of analyte ions and the full width at half maximum (FWHM) of the peak, respectively43.
