14 research outputs found
Recommendations for reporting ion mobility mass spectrometry measurements
© 2019 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc. 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 (K0) 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. © 2019 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc
Separation of phosphorothioated oligonucleotide diastereomers using multiplexed drift tube ion mobility mass spectrometry.
peer reviewedHydrophilic interaction liquid chromatography (HILIC) coupled to drift tube ion mobility spectrometry (DTIMS) was used to separate diastereomers of five-unit oligonucleotides containing 0, 1, 2 or 3 phosphorothioate (PS) linkages. Multiplexed DTIMS (where ions are pulsed into the drift tube according to a pre-encoded sequence) and post-acquisition processing using an innovative demultiplexing tool were investigated. The electric field inside the drift tube was optimized to achieve the highest resolving power. The entrance voltage providing the best two-peak resolution was -1000V with 3-bit multiplexing. Under optimized conditions, the eight diastereomers of an oligonucleotide with three PS linkages (5'-TC∗G∗T∗G-3') could be separated unambiguously. Indeed, those diastereomers differed in their collision cross section (CCS) values. The minimal CCS values difference between two adjacent diastereomers was 0.9% with maximal RSD on CCS values of 0.3%. The use of multiplexed ion mobility and the novel high-resolution demultiplexing tool represents a real breakthrough for resolution enhancement of diastereomers in linear DTIMS
Broadscale resolving power performance of a high precision uniform field ion mobility-mass spectrometer
An Interlaboratory Evaluation of Drift Tube Ion Mobility–Mass Spectrometry Collision Cross Section Measurements
Collision
cross section (CCS) measurements resulting from ion mobility–mass
spectrometry (IM-MS) experiments provide a promising orthogonal dimension
of structural information in MS-based analytical separations. As with
any molecular identifier, interlaboratory standardization must precede
broad range integration into analytical workflows. In this study,
we present a reference drift tube ion mobility mass spectrometer (DTIM-MS)
where improvements on the measurement accuracy of experimental parameters
influencing IM separations provide standardized drift tube, nitrogen
CCS values (<sup>DT</sup>CCS<sub>N2</sub>) for over 120 unique ion
species with the lowest measurement uncertainty to date. The reproducibility
of these <sup>DT</sup>CCS<sub>N2</sub> values are evaluated across
three additional laboratories on a commercially available DTIM-MS
instrument. The traditional stepped field CCS method performs with
a relative standard deviation (RSD) of 0.29% for all ion species across
the three additional laboratories. The calibrated single field CCS
method, which is compatible with a wide range of chromatographic inlet
systems, performs with an average, absolute bias of 0.54% to the standardized
stepped field <sup>DT</sup>CCS<sub>N2</sub> values on the reference
system. The low RSD and biases observed in this interlaboratory study
illustrate the potential of DTIM-MS for providing a molecular identifier
for a broad range of discovery based analyses
An Interlaboratory Evaluation of Drift Tube Ion Mobility–Mass Spectrometry Collision Cross Section Measurements
Collision
cross section (CCS) measurements resulting from ion mobility–mass
spectrometry (IM-MS) experiments provide a promising orthogonal dimension
of structural information in MS-based analytical separations. As with
any molecular identifier, interlaboratory standardization must precede
broad range integration into analytical workflows. In this study,
we present a reference drift tube ion mobility mass spectrometer (DTIM-MS)
where improvements on the measurement accuracy of experimental parameters
influencing IM separations provide standardized drift tube, nitrogen
CCS values (<sup>DT</sup>CCS<sub>N2</sub>) for over 120 unique ion
species with the lowest measurement uncertainty to date. The reproducibility
of these <sup>DT</sup>CCS<sub>N2</sub> values are evaluated across
three additional laboratories on a commercially available DTIM-MS
instrument. The traditional stepped field CCS method performs with
a relative standard deviation (RSD) of 0.29% for all ion species across
the three additional laboratories. The calibrated single field CCS
method, which is compatible with a wide range of chromatographic inlet
systems, performs with an average, absolute bias of 0.54% to the standardized
stepped field <sup>DT</sup>CCS<sub>N2</sub> values on the reference
system. The low RSD and biases observed in this interlaboratory study
illustrate the potential of DTIM-MS for providing a molecular identifier
for a broad range of discovery based analyses
Conformational Ordering of Biomolecules in the Gas Phase: Nitrogen Collision Cross Sections Measured on a Prototype High Resolution Drift Tube Ion Mobility-Mass Spectrometer
Ion mobility-mass spectrometry measurements
which describe the
gas-phase scaling of molecular size and mass are of both fundamental
and pragmatic utility. Fundamentally, such measurements expand our
understanding of intrinsic intramolecular folding forces in the absence
of solvent. Practically, reproducible transport properties, such as
gas-phase collision cross-section (CCS), are analytically useful metrics
for identification and characterization purposes. Here, we report
594 CCS values obtained in nitrogen drift gas on an electrostatic
drift tube ion mobility-mass spectrometry (IM-MS) instrument. The
instrument platform is a newly developed prototype incorporating a
uniform-field drift tube bracketed by electrodynamic ion funnels and
coupled to a high resolution quadrupole time-of-flight mass spectrometer.
The CCS values reported here are of high experimental precision (±0.5%
or better) and represent four chemically distinct classes of molecules
(quaternary ammonium salts, lipids, peptides, and carbohydrates),
which enables structural comparisons to be made between molecules
of different chemical compositions for the rapid “omni-omic”
characterization of complex biological samples. Comparisons made between
helium and nitrogen-derived CCS measurements demonstrate that nitrogen
CCS values are systematically larger than helium values; however,
general separation trends between chemical classes are retained regardless
of the drift gas. These results underscore that, for the highest CCS
accuracy, care must be exercised when utilizing helium-derived CCS
values to calibrate measurements obtained in nitrogen, as is the common
practice in the field
Enhancing Computational Tools for LC-IM-MS-Based Small Molecule Workflows (ASMS 2017)
Ion
mobility spectrometry (IMS) is a rapid and highly reproducible molecular-shape
separation technique. While IMS has shown great utility when coupled with MS
for analysis of complex samples, methods for processing the complex data
generated have lagged behind. In fact, the incorporation of this extra IMS separation
dimension requires upgrades and optimization of existing computational
pipelines and the development of new algorithmic strategies to fully exploit
the advantages of the technology. Here, we investigate MS pre-processing algorithms
to extend feature detection and quantification performance, as well as
integration of IMS collisional cross section (CCS) libraries into data analysis
tools for molecular characterization. These strategies were applied for
untargeted analyzes of biofluid samples to evaluate changes in endogenous
metabolites and xenobiotics