Phase Correction Vector for Mass Spectrum Peak Symmetry
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Solution Overview
Problem
Current Fourier transform mass spectrometry methods face challenges in achieving high resolving power due to phase variation issues, leading to asymmetrical peak shapes and reduced resolving power, with existing phase correction methods introducing sidelobes and spectral leakage, which affect mass accuracy and peak clarity.
Innovation Solution
A method and apparatus that utilize phase correction techniques to produce an enhanced mass spectrum by combining the magnitude and absorption spectra, reducing sidelobes and spectral leakage, while maintaining high resolving power, by determining the assumed start time and phase correction vector to align ion oscillations accurately within the mass analyser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If phase correction methods are applied to correct phase variation, then peak symmetry is improved, but sidelobes and spectral leakage are introduced
Solution Approach 1:
The patent applies a phase correction vector with frequency-dependent phase angles to correct the phase variation across different frequency components. By adjusting the phase parameter φ(f) = φ₀ + α·f for each frequency component, the method restores peak symmetry while minimizing sidelobe generation through optimized phase correction parameters
Solution Approach 2:
The patent introduces an enhanced spectrum calculation that combines the magnitude spectrum and phase-corrected absorption spectrum as intermediary steps. This intermediary approach allows selective use of phase correction benefits while mitigating its harmful effects through spectral combination
2Shape
If magnitude spectrum is used to display mass spectrum, then peak symmetry is achieved, but resolving power is reduced
Solution Approach 1:
The patent merges the magnitude spectrum and the phase-corrected absorption spectrum to create an enhanced spectrum. This combination allows the system to achieve both peak symmetry from the magnitude spectrum and high resolving power from the absorption spectrum, resolving the technical contradiction between these two parameters
3Manufacturing precision
If Fourier transformation with long detection time is used, then high resolving power is achieved, but acquisition speed is reduced
Solution Approach 1:
The patent changes the processing parameters by applying phase correction vectors and calculating enhanced spectra that combine magnitude and absorption components. This parameter change allows achieving high resolving power equivalent to long detection times but with shorter actual acquisition times, thereby improving acquisition speed while maintaining resolving power
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a 1.4 to 3.5-fold improvement in resolving power, allowing for faster mass spectrum acquisition with cleaner peaks and reduced spectral leakage, effectively addressing the limitations of previous methods.
Implementation Method 1
The oscillatory motion may be of various forms including, for example, circular oscillatory motion in the case of FT-ICR and axial oscillatory motion whilst orbiting about a central electrode in the case of the Orbitrap mass spectrometer. The oscillatory image charge in turn induces an oscillatory image current in circuitry connected to the detection electrodes
Implementation Method 2
Fourier transformation of the transient yields the oscillation frequencies associated with the particular detected oscillating ions and from the frequencies the m/z values of the ions can be determined
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
The invention provides a method of producing a mass spectrum, comprising: obtaining a transient from the oscillation of ions in a mass analyser; Fourier transforming the transient to obtain a complex spectrum having a real component and an imaginary component; and calculating an enhanced spectrum which comprises a combination of (i) and (ii) wherein (i) comprises a Positive spectrum; and (ii) comprises an Absorption spectrum. Also provided are an apparatus for producing a mass spectrum suitable for carrying out the method as well as a method of determining a phase correction for a complex spectrum obtained by Fourier transformation from a detected transient obtained from a mass analyser.