FT Mass Spectrometry Window Selection for m/z-Dependent Signal Fidelity
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Solution Overview
Problem
In Fourier Transform (FT) mass spectrometry, the use of a uniform FT window width for analyzing ions with different m/z ratios leads to loss of intensity fidelity in mass spectra due to mass dependence of the duration of the transient oscillating ion detection signal, resulting in sub-optimal signal-to-noise ratios for certain ions.
Innovation Solution
The implementation of a method to select an optimal FT window width based on the m/z ratio of target ions, which involves radially exciting ions within the FT mass analyzer and converting radial oscillations into axial oscillations, allowing for the optimization of signal intensity and peak width associated with the target ion by processing the transient oscillating ion detection signal with an FT window width that maximizes signal intensity and minimizes peak width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniform FT window width is used for analyzing ions with different m/z ratios, then the analysis process is simple, but the intensity fidelity is lost due to mass dependence of signal duration
Solution Approach 1:
The patent applies local quality by using different FT window widths for different m/z ratio ranges. Specifically, a first FT window width is used for ions with lower m/z ratios and a second FT window width is used for ions with higher m/z ratios. This localized adaptation of the window width parameter optimizes the signal-to-noise ratio and intensity fidelity for each mass range, resolving the contradiction between simple uniform analysis and precise intensity measurement.
2Ease of operation
If a single FT window width is applied to all ions, then the method is straightforward, but the signal-to-noise ratio is sub-optimal for certain ions
Solution Approach 1:
The patent changes the FT window width parameter based on the m/z ratio of the ions being analyzed. By adjusting this critical parameter according to the mass range, the system achieves optimal signal-to-noise ratios across different ion types. This parameter adaptation resolves the contradiction between operational simplicity and measurement reliability.
3Productivity
If a fixed FT window width is used, then the processing is efficient, but intensity loss occurs for ions with low m/z ratios
Solution Approach 1:
The patent implements local quality by applying different FT window widths to different m/z ratio ranges. A first FT window width is specifically used for ions with lower m/z ratios to prevent intensity loss, while a second FT window width is used for ions with higher m/z ratios. This localized optimization maintains processing efficiency while preventing intensity loss for specific ion populations.
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 minimizes and prevents the loss of intensity for ions with low m/z ratios, ensuring accurate mass peak intensities for ions with different masses and enhancing the signal fidelity in mass spectra by optimizing the FT window width for each target ion, thereby improving the overall performance of FT mass spectrometry.
Implementation Method 1
An RF voltage source can apply RF voltage(s) to the rods of the FT mass analyzer so as to generate an electromagnetic field within the ion passageway for radially confining the ions as they pass through the passageway
Implementation Method 2
The mass spectrometer can further include a voltage source for applying a voltage pulse to at least one of said rods (e.g., across two opposed rods) for radially exciting at least a portion of the ions at secular frequencies thereof such that an interaction of the radially excited ions with fringing fields in proximity of the outlet of the mass analyzer can convert the radial oscillations of the ions into axial oscillations
Data Source
AI summary
In one aspect, a mass spectrometer is disclosed, which comprises an ion source for receiving a sample and ionizing at least a portion of the sample to generate a plurality of ions, and a Fourier Transform (FT) mass analyzer that is configured to receive at least a portion of said plurality of ions at an inlet thereof. The ions exiting the FT are detected by an ion detector, which generates a transient oscillating ion detection signal. The analyzer processes the ion detection signal via application of an FT thereto, where the FT window width is selected to optimize a mass signal associated with at least one target ion of interest.