Recommendations for Reporting Ion Mobility Mass Spectrometry Measurements

Abstract

Here we present a guide to ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties of mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K 0 ) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N; (ii) ion mobility does not measure molecular surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model; (iii) methods relying on calibration are empirical (and thus may provide method-dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort toward establishing primary standards and reference materials for ion mobility, and provides recommendations to do so. #

Native mass spectrometry reveals the conformational diversity of the UVR8 photoreceptor

“…The result is a temporal separation of ions based upon the interaction of that ion with the gas, which in turn is dependent on its shape and charge (z), which is recorded as an arrival time distribution. The arrival time distribution of any given ion can be converted to a collision cross-section (CCS) distribution (18). The shape of this distribution for a species with a given nominal m/z is made up of the expected diffusion of the initial ion pulse as the ions traverse the cell as well as contributions from conformers or m/z coincident species, which may be higher-order oligomers or isomers.…”

Deep learning the collisional cross sections of the peptide universe from a million training samples

“…In TIMS the physical process is the same, except that the setup is reversed with the electrical field holding ions stationary against an incoming gas flow, prior to their controlled release from the device by lowering the electrical field 19,20 . In both cases, the measured ion mobility (reported as the reduced ion mobility coefficient K0) can be used to derive a collisional cross section (CCS), which is a measure of the ions' rotationally averaged gas phase conformation 21,22 . The CCS intrinsically depends on the ion structure, which is also illustrated by the fact that different classes of biomolecules (e.g.…”

Application of molecular dynamics simulation to improve the theoretical prediction for collisional cross section of aromatic compounds with long alkyl chains in crude oils

“…To test the applicability of proposed method, six more aromatic compounds with long alkyl chains were analyzed by theoretical calculation, and their experimental CCS values were taken from the literature. 8,50 The theoretical and experimental CCS values are listed in Table 2, and the figures are placed in the supporting information ( Figure S2_1-6, supporting information). The additional information required to create those figures is listed in Table S4_1-6 (supporting information).…”