Asymmetric Quadrupole Ion Trap Field for Mass Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The performance of ion trap mass spectrometers is limited by space charge density, which affects mass accuracy and resolution, as the number of ions that can be analyzed without impacting analytical performance is restricted.
Innovation Solution
A two-dimensional asymmetric substantially quadrupole field with significant hexapole and octapole components is established and maintained using a linear ion trap system, comprising specific RF and DC voltage configurations applied to pairs of rods and auxiliary electrodes, allowing for the adjustment of the phase shift and voltage magnitudes to optimize ion ejection and mass signal peak alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional quadrupole field is used in an ion trap mass spectrometer, then the device structure is simple and easy to operate, but the space charge density limits the number of ions that can be analyzed without impacting mass accuracy and resolution
Solution Approach 1:
The patent applies asymmetry by introducing hexapole and octapole field components to the conventional quadrupole field. This creates an asymmetric potential landscape that modifies ion trajectories and reduces space charge effects, allowing higher ion densities while maintaining mass measurement precision. The asymmetric field components are generated through specific voltage configurations on the rod electrodes.
Solution Approach 2:
The patent changes the field parameters by superimposing higher-order multipole components (hexapole and octapole) onto the fundamental quadrupole field. This parameter modification alters the ion motion dynamics and space charge distribution, enabling increased ion capacity without sacrificing mass accuracy. The field parameters are controlled through RF and DC voltage applications.
2Productivity
If more ions are introduced to increase analytical throughput, then productivity improves, but space charge effects cause peak migration and deteriorate mass accuracy
Solution Approach 1:
The patent converts the harmful space charge effect into a beneficial phenomenon by using the introduced hexapole and octapole field components to counteract peak migration. These additional field components create compensating forces that maintain ion trajectory stability even at high ion densities, thus converting the potential harm of high space charge into a benefit for maintaining both productivity and accuracy.
3Quantity of substance
If higher ion densities are used to improve productivity, then more ions can be analyzed, but the deleterious effects of space charge increase and impact analytical performance
Solution Approach 1:
The patent applies local quality by creating regions with different field characteristics through the superimposed multipole components. The hexapole and octapole fields create localized variations in the potential landscape that specifically address space charge effects in high-density regions, allowing high ion density to be maintained without the detrimental effects dominating the entire trap volume.
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 effectively reduces the deleterious effects of space charge, improving mass accuracy and resolution by allowing for higher ion densities without significant peak migration, enabling better analysis of ions across a range of mass-to-charge ratios.
Implementation Method 1
establishing and maintaining a two-dimensional asymmetric substantially quadrupole field having a first axis, a first axis potential along the first axis
Implementation Method 2
The first axis potential comprises a quadrupole harmonic of amplitude a hexapole harmonic of amplitude A31
Implementation Method 3
an octapole harmonic of amplitude A41, wherein in various embodiments A41 is greater than 0.001% of A21
Implementation Method 4
providing a first RF voltage to the first pair of rods at a first frequency and in a first phase, a second RF voltage to the second pair of rods at a second frequency equal to the first frequency
Implementation Method 5
a first DC voltage to the first pair of auxiliary electrodes, and a second DC voltage to the second pair of auxiliary electrodes
Data Source
AI summary
A system and method involving processing ions in a linear ion trap are provided, involving a two-dimensional asymmetric substantially quadrupole field having a hexapole and octopole component.