Exploring Ion Mobility Mass Spectrometry Data File Conversions to Leverage Existing Tools and Enable New Workflows.

Ion mobility (IM) is often combined with LC-MS experiments to provide an additional dimension of separation for complex sample analysis. While highly complex samples are better characterized by the full dimensionality of LC-IM-MS experiments to uncover new information, downstream data analysis workflows are often not equipped to properly mine the additional IM dimension. For many samples the data acquisition benefits of including IM separations are all that is necessary to uncover sample information and the full dimensionality of the data is not required for data analysis.

Construction of a Database of Collision Cross Section Values for Glycopeptides, Glycans, and Peptides Determined by IM-MS.

An ion mobility quadrupole time-of-flight mass spectrometer was used to examine the gas-phase structures of a set of glycopeptides resulting from proteolytic digestion of the well-characterized glycoproteins bovine ribonuclease B, human transferrin, bovine fetuin and human α-acid glycoprotein, the corresponding deglycosylated peptides, and the glycans released by the endoglycosidase PNGase F. When closely related glycoforms did not occur naturally, exoglycosidases were used to achieve stepwise removal of individual saccharide units from the nonreducing termini of the multiantennary structures. Collision cross sections (CCS) were calculated and plotted as a function of mass-to-charge ratio.

Separation and Identification of Isomeric Glycans by Selected Accumulation-Trapped Ion Mobility Spectrometry-Electron Activated Dissociation Tandem Mass Spectrometry.

One of the major challenges in structural characterization of oligosaccharides is the presence of many structural isomers in most naturally occurring glycan mixtures. Although ion mobility spectrometry (IMS) has shown great promise in glycan isomer separation, conventional IMS separation occurs on the millisecond time scale, largely restricting its implementation to fast time-of-flight (TOF) analyzers which often lack the capability to perform electron activated dissociation (ExD) tandem MS analysis and the resolving power needed to resolve isobaric fragments. The recent development of trapped ion mobility spectrometry (TIMS) provides a promising new tool that offers high mobility resolution and compatibility with high-performance Fourier transform ion cyclotron resonance (FTICR) mass spectrometers when operated under the selected accumulation-TIMS (SA-TIMS) mode.

Ion trapping for ion mobility spectrometry measurements in a cyclical drift tube.

A new ion trapping technique, involving the accumulation of ions in a cyclical drift tube, as a means of enhancing ion signals for scanning ion cyclotron mobility measurements has been modeled by computational simulations and demonstrated experimentally. In this approach, multiple packets of ions are periodically released from a source region into the on ramp region of the cyclical drift tube and these pulses are accumulated prior to initiation of the mobility measurements. Using this ion trapping approach, it was possible to examine ions that traversed between 1.

A scanning frequency mode for ion cyclotron mobility spectrometry.

A new operational mode for an ion cyclotron mobility spectrometry instrument is explored as a possible means of performing high-resolution separations. The approach is based on oscillating fields that are applied to segmented regions of a circular drift tube. Ions with mobilities that are resonant with the frequency of field application are transmitted while nonresonant species are eliminated.

High-resolution ion cyclotron mobility spectrometry.

A novel ion mobility spectrometry instrument incorporating a cyclotron geometry drift tube is presented. The drift tube consists of eight regions, four curved drift tubes and four ion funnels. Packets of ions are propagated around the drift tube by changing the drift field at a frequency that is resonant with the ion's drift time through each region.