Diverging Conical Duct Electrode for Mass Spectrometer Ion Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current mass spectrometers, particularly those coupled with nano-flow ESI ion sources, face inefficiencies in transferring ions from the atmosphere to the vacuum region, leading to reduced sensitivity and analysis speed due to rudimentary ion interfaces that lack effective desolvation and precise gas flow control.
Innovation Solution
A diverging conical duct electrode is used as an ion transfer device with an entrance aperture proximate to the electrospray ion source exit port, allowing ions to enter a vacuum housing, providing improved ion transfer efficiency by minimizing interaction with inner walls and maintaining a narrow, slowly diverging ion beam, which can be heated for desolvation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a small orifice is used in the first vacuum chamber, then the ion beam can be formed, but the ion beam becomes poorly collimated and quickly increases in diameter downstream, causing ion losses
Solution Approach 1:
The interface is divided into multiple functional components: a larger orifice for efficient ion production, a skimmer electrode for beam collimation, and a heated capillary for desolvation. This segmentation allows each component to optimize its specific function without compromising overall performance.
Solution Approach 2:
A skimmer electrode is introduced as an intermediary component between the orifice and the analysis chamber. This mediator creates a intermediate vacuum stage that allows the ion beam to be collimated without direct interaction between the high-pressure ion source and the high-vacuum analysis region.
2Reliability
If a skimmer electrode is positioned 4-7 mm downstream of the orifice, then ion passage into the next vacuum stage is improved, but the ion beam diameter increases and requires larger components
Solution Approach 1:
The skimmer electrode is nested within the heated capillary structure, with the skimmer positioned at the entrance of the capillary. This nested arrangement allows the skimmer to function at a shorter distance from the orifice while the capillary provides the extended path for desolvation and beam formation.
3Manufacturing precision
If heated gas curtain or heated laminar flow chamber is introduced, then ion desolvation is improved, but the device becomes expensive and requires precise controls for temperature and gas flows
Solution Approach 1:
The heated capillary serves multiple functions simultaneously: it provides structural support for the skimmer, creates a controlled heating environment for desolvation through resistive heating, and maintains a stable ion path. The system self-regulates without requiring external gas flow control or complex temperature management.
Solution Approach 2:
The complex mechanical gas flow control system is replaced with a simpler thermal field approach. Instead of using heated gas curtains or laminar flow chambers that require precise flow control, the invention uses resistive heating of the capillary wall to create a thermal gradient that facilitates desolvation.
4Temperature
If declustering potential is created between orifice and skimmer, then adiabatic expansion cooling is counteracted, but the voltage amplitude cannot be very large or it will induce dissociation of ions
Solution Approach 1:
Desolvation is performed preliminarily in the heated capillary before ions enter the high-voltage region between the skimmer and analysis chamber. This preliminary heating action removes solvent molecules before the ions are subjected to strong electric fields, preventing field-induced dissociation.
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 achieves ion transfer efficiencies up to 99% and 10 to 100 times higher transmitted ion current compared to traditional heated capillary interfaces, enhancing sensitivity and analysis speed without requiring precise gas flow control.
Implementation Method 1
the ion beam can be heated for desolvation
Implementation Method 2
heating the entire interface, and installing a heated laminar flow chamber (particle discriminator interface, PDI) in front of the orifice
Implementation Method 3
an electrospray ion source generating ions for analysis, the electrospray ion source comprising an exit port from which the ions are electrosprayed at atmosphere
Implementation Method 4
a first vacuum chamber evacuated by a roughing pump to pressures of about 1-10 Ton
Data Source
AI summary
An ion transfer device for transferring ions emerging from an electrospray ion source at atmosphere to a vacuum chamber includes an inner surface in the shape of a diverging conical duct. The ion transfer device has an entrance aperture for positioning proximate the exit port of the electrospray ion source emitter, the entrance aperture receiving the electrosprayed ions from the exit port of the electrospray ion source emitter at atmosphere, the diverging conical duct being an electrode toward which the ions migrate and having an exit aperture with an inner diameter larger than an inner diameter of its entrance aperture, the exit aperture enclosed in the vacuum chamber, the diverging conical duct transporting the ions from atmosphere to vacuum. The vacuum chamber can be a chamber of a vacuum housing enclosing a mass analyzer.