3 research outputs found
Phase-Constrained Spectrum Deconvolution for Fourier Transform Mass Spectrometry
This
Article introduces a new computationally efficient noise-tolerant
signal processing method, referred to as phased spectrum deconvolution
method (ΦSDM), designed for Fourier transform mass spectrometry
(FT MS). ΦSDM produces interference-free mass spectra with resolution
beyond the Fourier transform
(FT) uncertainty limit. With a presumption that the oscillation phases
are preserved, the method deconvolves an observed FT spectrum into
a distribution of harmonic components bound to a fixed frequency grid,
which is several times finer than that of FT. The approach shows stability
under noisy conditions, and the noise levels in the resulting spectra
are lower than those of the original FT spectra. Although requiring
more computational power than standard FT algorithms, ΦSDM runs
in a quasilinear time. The method was tested on both synthetic and
experimental data, and consistently demonstrated performance superior
to the FT-based methodologies, be it across the entire mass range
or on a selected mass window of interest. ΦSDM promises substantial
improvements in the spectral quality and the speed of FT MS instruments.
It might also be beneficial for other spectroscopy approaches which
require harmonic analysis for data processing
Determination of Collision Cross-Sections of Protein Ions in an Orbitrap Mass Analyzer
We
demonstrate a method for determining the collision cross-sections
(CCSs) of protein ions based on the decay rate of the time-domain
transient signal from an Orbitrap mass analyzer. Multiply charged
ions of ubiquitin, cytochrome <i>c</i>, and myoglobin were
generated by electrospray ionization of both denaturing solutions
and ones with high salt content to preserve native-like structures.
A linear relationship between the pressure in the Orbitrap analyzer
and the transient decay rate was established and used to demonstrate
that the signal decay is primarily due to ion-neutral collisions for
protein ions across the entire working pressure range of the instrument.
The CCSs measured in this study were compared with previously published
CCS values measured by ion mobility mass spectrometry (IMS), and results
from the two methods were found to differ by less than 7% for all
charge states known to adopt single gas-phase conformations
Parallelized Acquisition of Orbitrap and Astral Analyzers Enables High-Throughput Quantitative Analysis
The growing trend toward high-throughput
proteomics demands
rapid
liquid chromatography–mass spectrometry (LC–MS) cycles
that limit the available time to gather the large numbers of MS/MS
fragmentation spectra required for identification. Orbitrap analyzers
scale performance with acquisition time and necessarily sacrifice
sensitivity and resolving power to deliver higher acquisition rates.
We developed a new mass spectrometer that combines a mass-resolving
quadrupole, the Orbitrap, and the novel Asymmetric Track Lossless
(Astral) analyzer. The new hybrid instrument enables faster acquisition
of high-resolution accurate mass (HRAM) MS/MS spectra compared with
state-of-the-art mass spectrometers. Accordingly, new proteomics methods
were developed that leverage the strengths of each HRAM analyzer,
whereby the Orbitrap analyzer performs full scans with a high dynamic
range and resolution, synchronized with the Astral analyzer’s
acquisition of fast and sensitive HRAM MS/MS scans. Substantial improvements
are demonstrated over previous methods using current state-of-the-art
mass spectrometer