Auxiliary Electrode Ion Sequestration for Low-Fragmentation EAD
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Solution Overview
Problem
Conventional mass spectrometry systems face challenges in reducing internal fragmentation during electron-activated dissociation (EAD) of large, highly charged biological molecules, which limits the analyzable size of proteins and introduces background noise.
Innovation Solution
The method involves introducing ions and electrons into a dissociation instrument with auxiliary electrodes that sequester precursor ions, allowing them to interact with an electron beam in a controlled manner, thereby reducing the likelihood of secondary electron capture and internal fragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transverse beam of electrons is injected into an MS instrument to perform electron-activated dissociation, then the capability to dissociate bio-molecules is improved, but internal fragmentation increases due to secondary electron capture by produced fragments
Solution Approach 1:
The patent applies preliminary action by temporarily trapping precursor ions in an ion trap before introducing the electron beam. This allows the ions to be held in a controlled environment where they can be selectively activated and dissociated, preventing random secondary electron capture that occurs in continuous flow-through modes. The ions are prepared and positioned before the dissociation event, enabling better control over the fragmentation process.
Solution Approach 2:
The patent employs periodic action by using pulsed electron beam injection rather than continuous electron flow. The electron beam is introduced in controlled pulses that coincide with specific trapping and isolation phases of the ion cycle. This periodic activation allows the system to alternate between ion accumulation, electron-induced dissociation, and fragment ejection phases, thereby reducing internal fragmentation from secondary electron capture.
2Productivity
If electrons are continuously introduced to maintain dissociation capability, then productivity is improved, but the likelihood of secondary electron capture and internal fragmentation increases
Solution Approach 1:
The patent implements periodic action by cycling through distinct operational phases: ion trapping, electron beam pulsing for dissociation, and fragment ejection. This periodic operation maintains high productivity by continuously processing ions through these phases while minimizing internal fragmentation through controlled, intermittent electron exposure rather than continuous electron introduction.
Solution Approach 2:
The patent achieves continuity of useful action by maintaining a continuous supply of precursor ions to the trap while applying periodic electron activation. The ion source continuously feeds ions into the trapping region, ensuring that during each electron pulse, there are sufficient precursor ions available for dissociation. This continuous ion supply combined with periodic activation maintains high productivity without the harmful effects of continuous electron exposure.
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 internal fragmentation, allowing for the analysis of larger proteins by ensuring that precursor ions are dissociated with minimal secondary fragmentation, thus improving the accuracy and clarity of mass spectrometry results.
Implementation Method 1
electron capture dissociation (ECD) using electrons having kinetic energies of 0 to 3 eV
Implementation Method 2
high energy electron ionization dissociation (HEEID) (electrons with kinetic energy greater than 13 eV)
Data Source
AI summary
An ion sequestering apparatus and methods or systems using one or more auxiliary electrodes in an ion reaction instrument having RF electrodes adapted to guide positively-charged precursor ins along a first axis, and an electron source for introduction of an electron beam along a second axis transverse to the first axis such that electron activated dissociation of the precursor ions into reaction products can occur, the auxiliary electrode configured to apply a supplemental AC signal to permit selective extraction of reaction products while sequestering precursor ions along the second central axis. For example, the supplemental AC signal can comprises an notched white noise signal with a notch that suppresses frequencies at which the precursor ions (and/or charge reduced species that have the same molecular mass but have a different charge state) would otherwise be excited.