Linear Ion Trap Mass Spectrometer Space Charge Management
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Solution Overview
Problem
Linear ion traps face challenges in maintaining high Duty Cycle and sensitivity during mass spectrometry due to space charge effects, particularly when increasing ion introduction rates or scan ranges, which degrade mass resolution and limit ion accumulation time.
Innovation Solution
The implementation of a mass spectrometer with a linear ion trap that uses supplemental AC voltages applied between linear ion trap rods, end lenses, or inserted lenses to control ion ejection and accumulation, allowing for simultaneous ion accumulation and selective ejection within different m/z ranges, thereby managing space charge and enhancing Duty Cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion accumulation time is increased to improve Duty Cycle, then Duty Cycle is improved, but space charge effects increase causing mass resolution to degrade
Solution Approach 1:
The patent dynamically adjusts the accumulation time parameter based on operating conditions, allowing the system to optimize the balance between Duty Cycle and mass resolution. The accumulation time is set to a predetermined value that maximizes productivity while maintaining acceptable mass resolution, and can be adjusted during operation to adapt to varying ion introduction rates and analytical requirements.
2Adaptability or versatility
If scan range is widened to improve versatility, then versatility is improved, but ion accumulation time must be reduced causing Duty Cycle to decrease
Solution Approach 1:
The patent segments the wide m/z scan range into multiple discrete accumulation cycles, each targeting specific m/z ranges. Instead of attempting to accumulate all ions across the entire scan range simultaneously (which would require prohibitively long accumulation times), the system performs sequential accumulations for different mass ranges, then ejects and proceeds to the next range. This segmentation enables comprehensive wide-range scanning while maintaining reasonable accumulation times and Duty Cycle.
Solution Approach 2:
The patent employs periodic accumulation and ejection cycles to systematically cover wide m/z ranges. The system accumulates ions for a predetermined period, ejects them for analysis, then immediately begins the next accumulation cycle for the subsequent m/z range. This periodic action allows the system to maintain high productivity while systematically covering extensive mass ranges through repeated cycles of accumulation and ejection.
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 suppresses space charge, enabling high-sensitivity analysis with improved Duty Cycle and the ability to scan wide m/z ranges, significantly increasing the ion accumulation capacity and maintaining high mass resolution.
Implementation Method 1
uses supplemental AC voltages applied between linear ion trap rods, end lenses, or inserted lenses to control ion ejection and accumulation
Implementation Method 2
a linear ion trap portion for accumulating the transported ions by a potential formed axially
Data Source
AI summary
A mass spectrometer includes: an ion source for ionizing a specimen to generate ions, an ion transport portion for transporting the ions, a linear ion trap portion for accumulating the transported ions by a potential formed axially, and a control portion of ejecting the ions within a second m/z range different from a first m/z range, from the linear ion trap portion, and substantially at the same timing as the timing of accumulating the ions within the first m/z range from the transport portion into the linear ion trap portion. The ion transportation portion having a mass selection means for selecting the ions in the first m/z range.