Kingdon Ion Trap Fragmentation for High-Resolution Mass Spectrometry
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Solution Overview
Problem
Current mass spectrometers, such as ICR-MS, face challenges in achieving high mass resolution for higher masses due to rapid resolution decline, and require complex and costly setups, whereas Kingdon ion traps lack efficient methods for acquiring fragment ion spectra from metastable ions.
Innovation Solution
A Kingdon ion trap mass spectrometer is used to introduce metastable ions near the potential well minimum, allowing them to decompose and then excite the fragment ions for harmonic oscillations, enabling high-resolution mass spectrum acquisition through image current measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ICR-MS is used to achieve high mass resolution, then mass resolution is improved, but device complexity and cost increase due to requirement of superconducting magnet
Solution Approach 1:
The patent replaces the mechanical superconducting magnet system of ICR-MS with an electrostatic field-based Kingdon ion trap system. The electrostatic potential well generated by specifically shaped electrodes confines ions and enables harmonic oscillations, eliminating the need for complex magnetic field generation hardware while achieving comparable or superior mass resolution.
Solution Approach 2:
The patent changes the fundamental operating parameter from magnetic field-based ion cyclotron resonance to electrostatic field-based harmonic oscillations. By shaping electrodes to create a quadratic electrostatic potential well, the system achieves ion confinement and oscillation with different physical principles, simplifying the overall device architecture.
2Device complexity
If Kingdon ion trap is used instead of ICR-MS, then device complexity is reduced, but capability to acquire fragment ion spectra from metastable ions is lost
Solution Approach 1:
The patent applies preliminary action by storing metastable ions in the electrostatic potential well before they decompose. The ions are confined in a narrow longitudinal slice near the potential minimum, allowing controlled storage time for decomposition to occur, after which fragment ions are excited and detected. This preliminary storage and controlled decomposition enables fragment ion spectrum acquisition in the simplified Kingdon ion trap system.
3Measurement precision
If resolution requirement is maintained for higher masses in ICR-MS, then mass resolution is preserved, but the system becomes less practical due to rapid resolution decline
Solution Approach 1:
The patent changes the mass-resolution relationship by using electrostatic harmonic oscillations where frequency is inversely proportional to the square root of mass (√m/z) rather than directly inversely proportional to mass (m/z). This parameter change in the oscillation frequency-mass relationship causes resolution to decline more slowly at higher masses, improving practicality while maintaining measurement precision.
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 method achieves high mass resolution and accuracy for fragment ions, with improved ion trap design allowing for efficient decomposition and analysis of metastable ions, reducing the need for complex setups and maintaining ultrahigh vacuum conditions.
Implementation Method 1
Kingdon ion traps are electrostatic ion traps in which the ions orbit with a predefined kinetic energy around an inner electrode arrangement or oscillate through an inner electrode arrangement
Implementation Method 2
the longitudinal potential well allows for harmonic oscillations of the ions in longitudinal direction
Implementation Method 3
the image currents of these oscillations can be measured at these half-shells as temporal transient signals
Implementation Method 4
their excess of internal energy causes most of the metastable ions to decompose ergodically to fragment ions
Data Source
AI summary
Fragment ion spectra are acquired in Kingdon ion traps that have a potential well for harmonic oscillations of the ions in the longitudinal direction and in which the ions can oscillate radially in a plane between two or more inner electrodes. Metastable ions, preferably produced by laser desorption, are introduced into the Kingdon ion trap close to the minimum of the longitudinal potential well and stored there locally for a predetermined time period. Excess internal energy in the metastable ions causes most of the ions to decompose ergodically to fragment ions. Then the fragment ions and any remaining analyte ions are excited to execute harmonic oscillations in the longitudinal potential well. The harmonic oscillations are measured as image currents, from which a high-resolution mass spectrum of the fragment ions can be calculated.