RF Ion Guide Electron Impact Ionization for Intact Ion Capture
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Solution Overview
Problem
Current mass spectrometry ion sources, such as electron impact (EI) and chemical ionization (CI), face challenges in generating high yields of intact ions, especially for large or fragile molecules, due to fragmentation and complex ion extraction processes, requiring frequent cleaning and tuning, and often necessitate separate sources for positive and negative ion generation.
Innovation Solution
A combined filament and RF only ion guide configuration that allows for direct ionization and capture of ions within an RF confinement field, enabling efficient transport and generation of both positive and negative ions with adjustable electron energy to control fragmentation, and integration with GC systems for multiplexing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electron impact ionization is used to generate high yields of ions, then ion production efficiency is improved, but molecule fragmentation increases reducing intact ion yield
Solution Approach 1:
The patent applies dynamic control of electron beam parameters (energy, current, pulse width) to match the specific ionization needs of different molecules. By dynamically adjusting electron energy below traditional 70 eV and using pulsed electron beams synchronized with ion extraction, the system achieves high ion production while minimizing fragmentation that would occur with constant high-energy bombardment
Solution Approach 2:
The invention fundamentally changes the electron energy parameter from the traditional fixed 70 eV to variable energies typically below 70 eV, and introduces pulsed timing parameters. These parameter changes reduce the kinetic energy transferred to molecules during ionization, thereby decreasing fragmentation while maintaining adequate ionization efficiency through optimized pulse duration and repetition rate
2Productivity
If complex ion extraction systems are used to capture ions, then ion capture efficiency is improved, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent merges the ionization chamber and ion guide into a single integrated RF-only ion guide structure. The RF field serves dual functions: confining electrons for ionization and guiding extracted ions simultaneously. This eliminates the need for separate extraction optics, reducing the number of components from multiple electrodes and lenses to a single RF-driven system
Solution Approach 2:
The RF-only ion guide performs multiple functions that traditionally required separate components: it confines electrons during ionization, accelerates ions away from the electron beam, and guides ions through the mass spectrometer. This multi-functional design reduces device complexity while maintaining high ion capture efficiency through the unified RF field
3Adaptability or versatility
If separate sources are used for positive and negative ion generation, then ionization specificity is improved, but device complexity and operation time increase
Solution Approach 1:
The system dynamically switches between positive and negative ion modes by controlling electron beam polarity and energy without physically changing sources. The electron beam can be rapidly switched between positive electron mode (for positive ions) and negative electron mode (for negative ions), enabling fast mode changes synchronized with GC elution patterns
Solution Approach 2:
A single ion source configuration generates both positive and negative ions by adjusting electron beam parameters. The same ion guide structure handles both ion types, eliminating the need for separate physical sources and reducing switching time from minutes to seconds by simply changing electrical parameters rather than mechanical configurations
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 configuration enhances ion yield and reduces fragmentation, allowing for high-efficiency ionization and capture of intact ions, improving sensitivity and reducing maintenance needs, while enabling flexible operation with multiple GCs and compatibility with various ionization modes.
Implementation Method 1
electrons with above 70 eV in collision with a gaseous sample... produced by a glowing filament of resistive materials
Implementation Method 2
Electrons with above 70 eV in collision with a gaseous sample result in striping one or more electrons from atoms or molecules within the sample. This process results in the creation of predominantly positively charged ions plus free electrons
Implementation Method 3
capture them in an RF only ion guide... ionization and capture of ions within an RF confinement field, enabling efficient transport
Data Source
AI summary
The present system is a filament and an ion guide configuration. The ion source and an ion guide are combined in one system to create a fast release of ions, with increased efficiency of ion transport. The present device is a high-efficiency ion source operating at very low up to a few Torr pressure. Ions generated from the source immediately introduced into or created in an ion guide. The ions are introduced in or around the zero field lines of the RF field. Therefore, they will be trapped under the influence of the RF field there and can be transported to the next region of the mass spectrometer device. One method of transferring ions is by using ion-guides. Multipole ion guides have efficiently transferred ions through a vacuum or partial vacuum into mass analyzers. In particular, multipole ion guides have been configured to transport ions from a higher pressure region of a mass spectrometer to the lower pressure and then vacuum where the analyzer is operational.