Ion Trap Electrode Asymmetry for High Resolution Mass Spectrometry
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Solution Overview
Problem
Conventional ion trap mass spectrometers face a trade-off between ion isolation resolution and capture efficiency, where improving one aspect often compromises the other, leading to suboptimal MSn spectra quality and detection sensitivity.
Innovation Solution
Designing an ion trap that forms a quadrupole electric field with a superimposed dodecapole electric field of higher order, where the polarities and strengths of the octupole and dodecapole fields relative to the quadrupole field are carefully controlled to achieve steep resonance curve slopes on both sides, ensuring high ion isolation resolution and capture efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ion trap is designed according to theoretical shape with quadrupole electric field only, then the ion trap structure is simple and easy to manufacture, but the ion isolation resolution is insufficient
Solution Approach 1:
The patent applies asymmetry by intentionally distorting the ion trap electrodes from their ideal theoretical shapes. Specifically, the end cap electrodes are shifted along the z-axis to create asymmetric electric field distribution, which generates multipole components (octupole, dodecapole) that improve ion isolation resolution while maintaining manufacturability
Solution Approach 2:
The patent changes geometric parameters of the ion trap electrodes, specifically the distance z0 between the central point and the top of end cap electrodes, and the slope of the hyperboloid. By optimizing these parameters, the patent achieves a balance between manufacturing simplicity and ion isolation resolution
2Productivity
If the end cap electrodes are shifted along z-axis to increase distance z0, then the ion capture efficiency is improved, but the ion isolation resolution deteriorates
Solution Approach 1:
The patent optimizes the distance parameter z0 and the hyperboloid slope to achieve optimal ion capture efficiency while preventing resolution deterioration. The specific parameter values are determined through theoretical analysis and experimental optimization
Solution Approach 2:
The patent creates a composite electric field structure by combining quadrupole field (from ideal electrode shapes) with multipole fields (from intentional distortions). This composite field configuration achieves both high ion capture efficiency and high ion isolation resolution simultaneously
3Stability of the object's composition
If the hyperboloid slope is made closer to the rotating hyperboloid of electrodes, then the ion trap approaches theoretical design, but the ion isolation resolution decreases
Solution Approach 1:
The patent deliberately introduces asymmetry by adjusting the hyperboloid slope to be closer to the rotating hyperboloid configuration. This asymmetric design generates necessary multipole components that improve ion isolation resolution while maintaining electrode configuration stability
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 enhances the resolution of ion isolation and maintains high ion capture efficiency, resulting in high-purity MSn spectra and improved detection sensitivity.
Implementation Method 1
capturing ions in a space by forming a quadrupole electric field and a multipole electric field of order higher than that
Implementation Method 2
forming a quadrupole electric field and a multipole electric field of order higher than that [of the quadrupole electric field]
Implementation Method 3
high-frequency voltage Vcos Ωt of high voltage is applied to the ring electrode 10
Data Source
AI summary
In a three-dimensional quadrupole-type ion trap, a shape and an arrangement of the ring electrode and the end cap electrodes 11 and 12 are shifted from an ideal state in which only a quadrupole electric field is formed, so that the polarities of the ratio of strength of an octupole electric field with respect to the strength of a quadrupole electric field and the ratio of strength of a dodecapole electric field with respect to the strength of the quadrupole electric field are different from each other, their absolute values are equal to or greater than 0.02, and the absolute value of the ratio of strength of the octupole electric field with respect to the strength of the dodecapole electric field is within the range of from 0.6 to 1.4.