Heated Sample Conduit for Atmospheric Ionization
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Solution Overview
Problem
Conventional atmospheric-pressure ionization techniques for mass spectrometry face issues with the entry of unwanted droplets and non-analytical material into the mass spectrometer, leading to contamination, reduced sensitivity, and inefficient ion extraction, particularly due to inadequate drying gas contact and incomplete desolvation.
Innovation Solution
The implementation of an ionization apparatus with a heated sample conduit and a nonlinear flow path, where drying gas is mixed with the sample material, enhancing desolvation and separation of ions from liquid droplets through increased collisions and thermal energy transfer, thereby improving the signal-to-noise ratio and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional atmospheric-pressure ionization techniques are used, then ionization of sample material can be achieved, but unwanted droplets and non-analytical material enter the mass spectrometer causing contamination and reduced sensitivity
Solution Approach 1:
The interface region is segmented into multiple functional zones: an ionization chamber at atmospheric pressure, a transition region with pressure gradient, and a vacuum chamber. This segmentation allows different processes (ionization, desolvation, ion extraction) to occur in optimized environments, preventing droplet contamination while maintaining ionization efficiency
Solution Approach 2:
A buffer gas (such as nitrogen or helium) is introduced as an intermediary medium between the atmospheric-pressure ionization source and the vacuum mass spectrometer. This buffer gas facilitates pressure transition, enhances desolvation through collisions, and selectively transports ions while excluding larger droplets, thereby reducing contamination
2Loss of substance
If drying gas is used to remove droplets, then some desolvation occurs, but contact between drying gas and sample material is inadequate leading to incomplete desolvation
Solution Approach 1:
The buffer gas flows continuously through the transition region, maintaining constant contact with the sample material throughout the pressure gradient zone. This continuous interaction ensures progressive desolvation as the sample transitions from atmospheric to vacuum pressure, achieving complete removal of solvent and droplets
Solution Approach 2:
The system exploits changes in pressure, temperature, and gas flow rate parameters along the transition region. Pressure decreases from atmospheric to vacuum levels, temperature may be elevated to enhance evaporation, and buffer gas flow rate is optimized to maximize collisions with sample material, collectively improving desolvation efficiency
3Device complexity
If a simple interface is used between atmospheric-pressure ionization and vacuum mass spectrometer, then device complexity is reduced, but ion extraction efficiency is poor
Solution Approach 1:
The buffer gas serves multiple functions simultaneously: it acts as a pressure transition medium, a desolvation agent through thermal and collisional effects, an ion transport vehicle, and a contaminant filter. This multi-functionality achieves high ion extraction efficiency without requiring complex additional components
Solution Approach 2:
The system replaces complex mechanical ion pumping mechanisms with a gas-dynamic approach. Instead of using mechanical means to extract ions across the pressure boundary, the buffer gas flow creates a controlled pressure gradient that naturally drives ion transport while excluding droplets, simplifying the overall interface design
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 desolvation, increases ion signal strength, and reduces chemical background, resulting in improved sensitivity and reduced contamination within the mass spectrometer.
Implementation Method 1
enhancing desolvation and separation of ions from liquid droplets through increased collisions and thermal energy transfer
Implementation Method 2
enhancing desolvation and separation of ions from liquid droplets through increased collisions and thermal energy transfer
Implementation Method 3
enhancing desolvation and separation of ions from liquid droplets
Implementation Method 4
enhancing desolvation and separation of ions from liquid droplets through increased collisions and thermal energy transfer
Implementation Method 5
ionizes sample material performed at pressures above vacuum
Data Source
AI summary
Sample material ionized in a sample receiving chamber is flowed into a sample conduit. Drying gas may also flow into the sample conduit and may be heated. The pressure and length of the sample conduit may be provided according to the product 50 or greater Torr−cm. The sample conduit may include a turn. The sample conduit may lead to an ion extraction chamber at which a sampling orifice may lead to a mass spectrometer. The diameter of the sample conduit may be larger than the diameter of the sampling orifice. An electrical field may be applied in the ion extraction chamber to slow incoming ions. A voltage jump may be applied to the sample conduit.