Atmospheric Pressure Interface for Mass Spectrometry Ion Transfer
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Solution Overview
Problem
Existing spectrometry systems face inefficiencies in interfacing atmospheric pressure ionization apparatuses with spectrometers operating at vacuum conditions due to challenges in focusing ions through electrostatic fields amidst strong gas dynamics, leading to difficulties in ion transfer and separation.
Innovation Solution
An atmospheric pressure interface is designed with an ionization chamber and an interface device featuring an ion inlet and a gas passage, where the gas passage has greater conductance than the ion inlet, allowing most gas to be diverted externally, and a static electric field is applied to focus ions preferentially into the ion inlet, optimizing ion transfer to a reduced-pressure region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas throughput of the AP interface is increased to capture more ions, then ion capture efficiency is improved, but gas separation becomes more difficult and system complexity increases
Solution Approach 1:
The interface device is segmented into separate functional components: an ion inlet for ion transmission and a gas passage for gas removal. This segmentation allows independent optimization of ion capture and gas management, enabling high ion capture efficiency without requiring complex integrated solutions like electrodynamic ion funnels.
Solution Approach 2:
The gas passage extracts excess gas from the ionization chamber before it can interfere with ion analysis. By removing gas early in the interface, the system achieves efficient ion capture while maintaining simpler downstream vacuum requirements, eliminating the need for complex multi-stage pumping systems.
2Manufacturing precision
If electrostatic fields are used to focus ions into the ion transfer component, then ion focusing is improved, but gas dynamics interfere with ion motion
Solution Approach 1:
The interface device acts as an intermediary component between the atmospheric pressure ionization chamber and the vacuum spectrometer. It provides a transition zone where ions can be focused using electrostatic fields while gas is simultaneously removed through the gas passage, mediating between the conflicting requirements of ion focusing and gas management.
Solution Approach 2:
Different regions of the interface device have different functional qualities: the ion inlet region is optimized for electrostatic ion focusing while the gas passage region is optimized for gas removal. This local differentiation allows electrostatic fields to focus ions effectively without being overwhelmed by gas dynamics in other regions.
3Productivity
If ion transfer is performed at higher pressure to improve ion capture, then ion capture efficiency is improved, but ion separation becomes more difficult
Solution Approach 1:
The gas passage performs preliminary gas removal action before ions enter the vacuum spectrometer for separation. By removing excess gas early in the interface at atmospheric pressure where gas removal is more efficient, ions can be captured effectively and then separated with high precision in the vacuum environment without gas interference.
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 focusing and separation efficiency, reducing gas pressure in the spectrometer's first stage, simplifying the system, and enabling broader ion range transmission with stable signals, potentially eliminating the need for complex interface components like ion funnels.
Implementation Method 1
the interface device is configured for applying a static electric field effective for focusing ions in the ionization chamber preferentially into the ion inlet
Implementation Method 2
applying a static electric field effective for focusing ions
Implementation Method 3
the gas passage has a greater gas conductance than the ion inlet such that most gas flowing into the interface device flows into the gas passage and not the ion inlet
Data Source
AI summary
An atmospheric pressure (AP) interface for a spectrometer includes wall for separating an ionization chamber from a reduced-pressure region of the spectrometer, an ion inlet defining an ion path from the ionization chamber to the reduced-pressure region, and a passage defining a gas path from the ionization chamber to a gas outlet external to the reduced-pressure region. The passage may have a greater gas conductance than the ion inlet such that most gas into the passage and not the ion inlet. The interface device is configured for applying a static electric field effective for focusing ions in the ionization chamber preferentially into the ion inlet.