A W-Geometry Ortho-TOF MS with High Resolution and Up to 100% Duty Cycle for MS/MS.

Orthogonal injection time-of-flight (orthoTOF) mass spectrometry (MS) is the most prevalent form of TOFMS, owing to its greater control over incoming ion energy, the ability to correct for aberrations in incoming ion velocity and position, and its ability to provide an entire mass spectrum within a single scan. However, the duty cycle of orthoTOFMS is low compared with scanning analyzers, which can have 100% duty cycle when measuring a single type of ion. Typical duty cycles for orthoTOFMS range from 1% to 30%, depending on instrument geometry.

A novel ion trap that enables high duty cycle and wide m/z range on an orthogonal injection TOF mass spectrometer.

Although TOF analyzers with orthogonal ion injection provide the whole spectrum without scanning, their duty cycle is low compared with scanning analyzers in single ion monitoring mode. Typical duty cycle is in the range of 5% to 30% depending on the instrument geometry and ion m/z value. We present here a novel trapping/releasing setup, which offers the duty cycle near 100% over a wide range.

Electrospray ionization mass spectrometry and ion mobility analysis of the 20S proteasome complex.

Mass spectrometry and gas phase ion mobility [gas phase electrophoretic macromolecule analyzer (GEMMA)] with electrospray ionization were used to characterize the structure of the noncovalent 28-subunit 20S proteasome from Methanosarcina thermophila and rabbit. ESI-MS measurements with a quadrupole time-of-flight analyzer of the 192 kDa alpha7-ring and the intact 690 kDa alpha7beta7beta7alpha7 are consistent with their expected stoichiometries. Collisionally activated dissociation of the 20S gas phase complex yields loss of individual alpha-subunits only, and it is generally consistent with the known alpha7beta7beta7alpha7 architecture.

Collisional cooling of large ions in electrospray mass spectrometry.

Collisional cooling of ions in the rf-only multipole guides has become a method of choice for coupling electrospray sources to various mass analyzers. Normally parameters of such ion guides (length, pressure) provide enough thermalization and focusing for ions in a wide mass range. Noncovalent complexes, however, have more compact conformations than denatured biomolecules of similar mass and, therefore may not be transmitted efficiently through standard ion guides, as demonstrated by theoretical analysis, simulations, and experiments.

Quantitative profiling of phospholipids by multiple precursor ion scanning on a hybrid quadrupole time-of-flight mass spectrometer.

A hybrid quadrupole time-of-flight mass spectrometer featured with ion trapping capabilities was employed for quantitative profiling of total extracts of endogenous phospholipids. Simultaneous acquisition of precursor ion spectra of multiple fragment ions allowed detection of major classes of phospholipids in a single experiment. Relative changes in their concentration were monitored using a mixture of isotopically labeled endogenous lipids as a comprehensive internal standard.