Radial Activation of Ion Trap for ETD Structural Analysis
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Solution Overview
Problem
Current methods for analyzing molecules, particularly biomolecules, face limitations in efficiently achieving electron transfer dissociation (ETD) yields and structural information due to factors like proton transfer interference and varying charge states, which affect the accuracy and completeness of peptide and protein characterization.
Innovation Solution
The method involves using a linear ion trap with a dipolar AC voltage applied transverse to the ion trap axis to facilitate radial activation of ions during cation transmission-mode electron transfer ion/ion reactions, enhancing ETD yields and structural information by minimizing proton transfer contributions and optimizing ion/ion reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electron transfer dissociation (ETD) methods are used in ion traps, then peptide and protein structural information can be obtained, but proton transfer interference reduces the accuracy and completeness of characterization
Solution Approach 1:
The patent divides the ion trap operation into distinct phases: a first time period dedicated to ion/ion reactions where proton transfer is minimized, and a second time period for collisional activation. This temporal segmentation allows selective enhancement of ETD products while suppressing proton transfer interference, thereby improving structural information accuracy.
Solution Approach 2:
The patent employs periodic application of activation fields during the second time period to induce collisional activation of ETD product ions. This periodic action enhances the fragmentation and structural information from ETD products while the first time period maintains low proton transfer conditions, resolving the contradiction between obtaining structural information and avoiding proton transfer interference.
2Productivity
If collisional activation is applied to enhance ETD yields, then more structural information is obtained, but proton transfer contributions increase
Solution Approach 1:
The patent segments the activation process into two distinct time periods: a first time period with minimal collisional activation where ion/ion reactions occur with reduced proton transfer, and a second time period where collisional activation is applied to enhance ETD yields. This segmentation allows the system to achieve high productivity while controlling harmful proton transfer contributions through temporal separation of reaction and activation phases.
Solution Approach 2:
The patent performs the ion/ion reactions during the first time period before applying collisional activation in the second time period. This preliminary action ensures that ETD products are formed first under conditions that minimize proton transfer, and only then are these products activated to enhance yields, thereby achieving high productivity without excessive proton transfer interference.
3Manufacturing precision
If low collision-energy regime CID is used for slow activation, then ion dissociation occurs, but the process takes milliseconds to seconds which reduces analysis efficiency
Solution Approach 1:
The patent employs periodic collisional activation during the second time period to achieve rapid ion dissociation. Instead of using slow continuous low-collision-energy activation, the system applies periodic activation fields that efficiently dissociate ions within microseconds, dramatically reducing the activation time while maintaining complete ion dissociation, thus resolving the contradiction between dissociation completeness and analysis efficiency.
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 increases the yield and extent of structural information from ETD, improving the characterization of peptides and proteins by enhancing the formation of c- and z-type ions while minimizing contributions from proton transfer products, thus improving the accuracy of mass spectrometry analysis.
Implementation Method 1
a dipolar AC voltage is applied transverse to the ion trap axis to facilitate radial activation of ions during cation transmission-mode electron transfer ion/ion reactions
Implementation Method 2
providing a ion trapping volume; injecting a first population of ions into the ion trapping volume so that the first population is stored in the trapping volume
Implementation Method 3
performing mass spectrometry on ionic products ejected from the ion trap
Implementation Method 4
The ion/ion reaction analogue to ECD is electron transfer dissociation (ETD), where the electron is transferred (ET) from an anion to a multiply-charged peptide or protein cation
Data Source
AI summary
A method and apparatus for radial activation of transmission-mode electron transfer ion/ion reactions using a dipolar AC field applied transverse to a transit direction is disclosed. Increases in fragment ion yields and structural information from electron transfer dissociation (ETD) were observed. The method may be used for transmission mode ETD for relatively low charge states of peptides and proteins.