Orthogonal Acceleration Electrode Duty Cycle Optimization
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Solution Overview
Problem
Conventional orthogonal acceleration Time of Flight mass analyzers have a limited duty cycle, typically around 20-25%, with lower efficiency for ions with lower mass-to-charge ratios, and existing methods to enhance duty cycle are only effective for narrow ranges of mass-to-charge ratios, resulting in reduced sampling efficiency for a wide range of ions.
Innovation Solution
The method involves releasing multiple packets of ions from an ion trap or ion guide and synchronizing the orthogonal acceleration voltage with each packet's release, allowing for multiple energizations of the orthogonal acceleration electrode at varying delay times before subsequent packet releases, thereby increasing the duty cycle across a wide range of mass-to-charge ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single orthogonal acceleration pulse is applied per ion packet release, then the duty cycle for ions of a specific mass-to-charge ratio can be maximized to 100%, but the sampling efficiency for ions with other mass-to-charge ratios drops to zero
Solution Approach 1:
The patent segments the ion packet release and acceleration process into multiple discrete events. Instead of a single acceleration pulse per packet, multiple acceleration pulses are applied at different delay times, with each pulse optimized for a specific mass-to-charge ratio range. This segmentation allows the system to maintain high duty cycles across multiple ion species rather than optimizing for just one.
Solution Approach 2:
The patent implements periodic action by applying multiple orthogonal acceleration pulses at regularly spaced delay times within each ion packet cycle. The acceleration electrode is energized at multiple predetermined delay times (e.g., first delay time, second delay time, etc.) before the next ion packet release, creating a periodic acceleration pattern that captures ions of different velocities systematically.
2Adaptability or versatility
If the orthogonal acceleration electrode is energized multiple times at different delay times, then the duty cycle is enhanced across a wide mass-to-charge ratio range, but the device complexity increases
Solution Approach 1:
The patent applies universality by using a single orthogonal acceleration electrode to perform multiple functions - it accelerates ions of different mass-to-charge ratios at different delay times within the same operational cycle. The same physical component serves multiple purposes across the mass spectrum, avoiding the need for multiple separate acceleration systems and reducing overall device complexity.
Solution Approach 2:
The patent changes the temporal parameter (delay time) of the acceleration pulse to adapt to different ion mass-to-charge ratios. By varying the delay time between ion packet release and acceleration pulse application, the system optimizes duty cycle for different ion velocities without changing the physical configuration of the acceleration electrode or adding complex mechanical adjustments.
3Measurement precision
If ions are released in packets with constant energy from an ion trap, then the duty cycle for transmitted ions can reach 100%, but ions with other mass-to-charge ratios suffer reduced sampling efficiency
Solution Approach 1:
The patent applies preliminary action by releasing ions into the drift region before the orthogonal acceleration pulse is applied. The ion packet is released and begins drifting toward the acceleration region, and the acceleration pulse is timed to arrive at a predetermined delay time when ions of the target mass-to-charge ratio reach the acceleration region. This preliminary release allows optimal timing for subsequent acceleration.
Solution Approach 2:
The patent introduces dynamics by allowing multiple acceleration events within a single ion packet cycle. The system dynamically adjusts the timing of acceleration pulses based on the velocity distribution of ions with different mass-to-charge ratios. This dynamic, multi-stage acceleration approach within each cycle enables the system to adapt to the varying arrival times of different ion species.
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 significantly enhances the duty cycle to nearly 100% for ions of interest and maintains a substantial duty cycle across a wide mass-to-charge ratio range, improving overall sampling efficiency and ion signal intensity without sacrificing sensitivity for higher mass-to-charge ratio ions.
Implementation Method 1
An orthogonal acceleration electric field is periodically applied across the orthogonal acceleration region in order to orthogonally accelerate ions into the drift region of the Time of Flight mass analyser
Implementation Method 2
orthogonal acceleration Time of Flight mass analyser
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2D
AI summary
A mass spectrometer is disclosed comprising an orthogonal acceleration Time of Flight mass analyser. A pulse or packet of ions is released either from an ion trap (7) or alternatively from a travelling wave ion guide arranged upstream of an orthogonal acceleration electrode (2) which forms part of the Time of Flight mass analyser. Ions in the pulse or packet of ions which is released become temporally dispersed and the orthogonal acceleration electrode (2) is energised multiple times prior the release of a subsequent pulse or packet of ions.