Multipole Ion Guide with Auxiliary Electrodes for Low m/z Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional mass spectrometry systems face challenges in maintaining sensitivity due to contamination from unwanted ions and neutral molecules, which can foul downstream components and require extensive cleaning, thereby increasing maintenance costs and reducing throughput.
Innovation Solution
The use of an ion guide with auxiliary electrodes in a high-pressure region allows for selective transmission of ions of interest by radially deflecting low m/z ions, preventing them from entering the downstream mass analyzer and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the inlet orifice size is increased to increase ion transmission and sensitivity, then the number of ions of interest entering the ion guide increases, but more unwanted ions and neutral molecules also enter the vacuum chamber, increasing contamination of downstream components
Solution Approach 1:
The ion guide system is segmented into multiple functional zones: an upstream section for ionization and initial filtering, a multipole ion guide section for selective ion transmission based on m/z ratios, and a downstream section for mass analysis. This segmentation allows the system to simultaneously achieve high sensitivity through increased orifice size while preventing contamination through selective filtering at each stage.
Solution Approach 2:
The multipole ion guide acts as an intermediary component between the ion source and the mass analyzer. It selectively transmits ions of interest while filtering out unwanted ions and neutral molecules, thereby mediating between the need for high ion transmission (sensitivity) and the need to prevent contamination of downstream components.
2Device complexity
If conventional ion guides are used without auxiliary electrodes, then the structure is simpler, but they cannot selectively filter low m/z ions, leading to increased contamination of downstream optics
Solution Approach 1:
The ion guide electrodes are segmented into conventional RF-driven rods and auxiliary electrodes that are not directly driven by RF signals. This segmentation allows the auxiliary electrodes to create static or slowly varying electric fields that complement the RF fields, enabling selective filtering of low m/z ions without requiring complete redesign of the ion guide structure.
Solution Approach 2:
By introducing auxiliary electrodes with different electrical characteristics (non-RF driven), the system changes the electrical field parameters within the ion guide. This allows creation of additional filtering mechanisms that can selectively affect low m/z ions while maintaining transmission of higher m/z ions of interest, thereby reducing contamination without excessive structural complexity.
3Measurement precision
If downstream components are cleaned frequently to maintain performance, then sensitivity is maintained, but throughput decreases due to venting and disassembly requirements
Solution Approach 1:
The multipole ion guide performs preliminary filtering of unwanted ions and neutral molecules before they can contaminate downstream components. By removing contaminants upstream, the system prevents fouling of downstream optics, eliminating the need for frequent cleaning and venting operations, thereby maintaining both sensitivity and high throughput.
Solution Approach 2:
The system converts the potentially harmful effect of increased ion transmission (which would normally lead to more contamination) into a benefit by using the multipole ion guide to selectively filter ions. The high ion flux is maintained while contamination is prevented, transforming what would be a harmful situation into a beneficial one where high sensitivity and low maintenance are achieved simultaneously.
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 enhances the sensitivity of mass spectrometry instruments by selectively filtering ions based on their mass-to-charge ratios, thereby reducing contamination in downstream components and maintaining instrument performance.
Implementation Method 1
a radio frequency (RF) signal applied to the ion guide provides collisional cooling and radial focusing along the central axis of the ion guide
Implementation Method 2
employ an ion guide having a plurality of auxiliary electrodes included therein that can be configured to radially deflect from the internal volume of the ion guide at least a portion of low m/z ions so as to prevent transmission of such ions into the downstream, high-vacuum portion
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Systems and methods described herein relate to a mass spectroscopy system having multipole ion guides that can receive ions from an ion source for transmission to downstream mass analyzers, while preventing unwanted ions from being transmitted into the high-vacuum chambers of mass spectrometer systems. At least one ion guide can have two or more auxiliary electrodes that extend along at least a portion of the ion guide. A power supply provides an RF voltage to the poles of the ion guide for radially confining the ions within the internal volume of the ion guide. The auxiliary electrodes are also provided with an auxiliary electrical signal that can selectively radially deflect from the internal volume at least a portion of low m/z ions so as to prevent transmission of undesired low m/z ions into the downstream mass analyzers.