Ion Trap Segmentation for ETD Fragmentation Efficiency
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Solution Overview
Problem
Current mass spectrometry techniques face challenges in efficiently fragmenting ions, particularly due to limitations in ion traps that hinder processes like Electron Transfer Dissociation (ETD) and Electron Capture Dissociation (ECD), which are essential for analyzing organic compounds, as they struggle to confine and interact ions of opposing charges effectively.
Innovation Solution
The method involves an ion trap with an elongate multipole electrode assembly that applies RF pseudopotentials and DC biases to create overlapping potential wells, allowing for the independent confinement and interaction of ions of opposing charges, enhancing ion confinement and fragmentation efficiency through Electron Transfer Dissociation (ETD) and potentially other methods like UVPD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a linear multipole ion trap is used to confine ions, then radial confinement is achieved through RF pseudopotential, but ions of opposing charges cannot be effectively confined and interact due to different responses to static electric fields
Solution Approach 1:
The ion trap is divided into multiple potential wells (first potential well for precursor ions, second potential well for reagent ions) that are spatially separated but overlap in the radial direction. This segmentation allows different charge types to be confined in different axial regions while enabling radial interaction through the overlap zone.
Solution Approach 2:
The solution transitions from attempting to confine opposing charges in the same spatial region to confining them in different axial dimensions while allowing radial overlap. This dimensional separation resolves the conflict between electrostatic repulsion and the need for interaction.
2Productivity
If precursor ions and reagent ions are confined in the same volume for interaction, then ion/ion interactions occur, but product ions are destroyed by continued interactions (self-quenching)
Solution Approach 1:
The trap is segmented into distinct potential wells that separate precursor ions, reagent ions, and product ions into different axial regions. This spatial segmentation allows the fragmentation reaction to occur in a controlled zone while protecting product ions from further interactions.
Solution Approach 2:
Product ions are extracted from the interaction region by confining them in a separate potential well. This removes them from the environment where further destructive interactions could occur, preserving the fragmentation products for analysis.
3Adaptability or versatility
If RF fields are applied for radial confinement, then ion confinement is achieved, but low energy electrons cannot be trapped as they maintain thermal energies for only a fraction of a microsecond
Solution Approach 1:
The system uses dynamic RF fields for radial confinement of ions while employing static or slowly varying DC potentials for axial confinement. This dynamic-static field combination creates conditions suitable for both ion trapping and electron capture dissociation.
Solution Approach 2:
The patent changes the field parameters by using different frequency and amplitude characteristics for RF and DC components, creating a composite field environment that accommodates both fast-moving ions and slow thermal electrons.
4Ease of operation
If multiple potential wells are used to confine different ion types, then selective confinement and interaction are improved, but device complexity increases
Solution Approach 1:
The multipole electrode assembly serves multiple functions: it generates RF pseudopotentials for radial confinement, establishes DC potentials for axial confinement, and creates the overlapping potential well structure. This multi-functionality reduces the need for separate dedicated components.
Solution Approach 2:
The patent combines radial and axial confinement mechanisms into a unified electrode structure where RF and DC potentials work together to create the multi-well configuration. This merging simplifies the overall device architecture compared to using separate systems for each function.
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 increases the rate of ion/ion interactions, improves fragmentation efficiency, and reduces the destruction of product ions by allowing them to escape the trap, leading to a more effective MS/MS analysis and reduced self-quenching of the fragmentation reaction.
Implementation Method 1
The first ions are radially confined within the elongate ion channel by applying an RF pseudopotential to the elongate multipole electrode assembly
Implementation Method 2
The first ions are axially confined to a first volume within the ion channel by applying a first potential well to the elongate ion channel
Implementation Method 3
cooling the first ions and the second ions in the ion trap
Implementation Method 4
allowing the first ions and the second ions to interact such that the first ions and/or the second ions are fragmented to produce product ions
Data Source
AI summary
A mass spectrometer includes a controller operable to: transfer first ions of a first charge into an ion trap; apply an RF pseudopotential that radially confines the first ions in an elongate ion channel of the trap; generate a first potential well that confines the first ions within a first volume; after a specified pre-cooling time, transfer second ions of a second, opposite charge into the trap; apply one or more additional DC potentials that generate a second potential well that confines the second ions within a second volume, the first potential well being within the second potential well; cause, after cooling the second ions, the first ions and the second ions to interact and generate product ions; and generate at least one third potential well that confines the product ions, that is adjacent to the second potential well and that has a same polarity as the first potential well.