Differential Ion Mobility with Independent Gas Velocity Control
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Solution Overview
Problem
Existing ion mobility spectrometry methods struggle with controlling gas flow velocity and pressure independently, which affects the accuracy and efficiency of differential ion mobility analysis, particularly in high-field asymmetric IMS (FAIMS) and differential mobility spectrometry (DMS).
Innovation Solution
The method involves generating ions from a sample using a supersonic jet of buffer gas, controlling the gas flow rate and pressure in a vacuum region, and adjusting the gas velocity to achieve pre-set target values, enabling precise differential ion mobility analysis by using a supersonic jet and partitioning the vacuum region to minimize pressure differences, thereby allowing independent control of gas flow velocity and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas flow rate and pressure are controlled together in conventional IMS, then the system operation is simplified, but the accuracy and efficiency of differential ion mobility analysis deteriorates due to inability to independently optimize gas velocity and pressure
Solution Approach 1:
The vacuum region is divided into multiple sealed chambers (first vacuum chamber containing ion source and drift region, second vacuum chamber containing detector). Each chamber can have independent pressure control, allowing gas velocity and pressure to be optimized independently for different functional requirements while maintaining overall system operation.
2Quantity of substance
If gas pressure is increased to improve ion mobility measurement, then ion signal strength improves, but gas flow velocity control becomes less precise
Solution Approach 1:
By segmenting the vacuum system into pressure-controlled chambers, the drift region can operate at higher pressure for stronger ion signals while the detector chamber operates at lower pressure for precise velocity control and background reduction.
3Productivity
If gas flow velocity is increased to improve analysis speed, then productivity increases, but separation efficiency and detection accuracy deteriorate
Solution Approach 1:
The system allows dynamic adjustment of gas flow velocity and pressure parameters. The gas flow rate can be optimized during different stages of analysis, and multiple operating conditions can be switched to balance between analysis speed and separation efficiency based on specific analytical requirements.
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 accuracy and sensitivity of ion mobility analysis by ensuring consistent gas flow velocity and pressure, improving the separation and detection of ions based on their mobility characteristics.
Implementation Method 1
delivering them entrained in a buffer gas (preferably the buffer gas is a supersonic jet) into an ion mobility analyser in a vacuum region
Implementation Method 2
delivering the ions through an ion inlet into a vacuum region... within which the ions are entrained to enter the drift region
Implementation Method 3
A transverse electric field, E, is applied across this analytical gap using an asymmetric voltage waveform
Implementation Method 4
ions are characterised in a supporting buffer gas atmosphere... in terms of the speed at which ensembles of those ions progress through a supporting gas atmosphere when urged through it by an applied electric field
Implementation Method 5
controlling the gas flow rate and pressure in a vacuum region, and adjusting the gas velocity to achieve pre-set target values
Implementation Method 6
measuring a velocity of gas flow along the drift region
Data Source
AI summary
A method of analyzing ions comprising generating ions from a sample in an ion source, delivering them into a vacuum region of a vacuum enclosure comprising an ion mobility analyser having an ion drift region formed between opposing electrodes defining an analytical gap. The ions emerge from the ion inlet as a supersonic jet of a buffer gas within which the ions are entrained to enter the drift region and, e.g., prior to mass spectral analysis of the ions in a downstream vacuum region, conducting differential ion mobility analysis of the ions in the first vacuum region. Prior to conducting differential ion mobility analysis (e.g., and mass spectral analysis) according of the ion, the method comprisesa) changing a rate of flow of gas into or out of the vacuum region;b) measuring a gas pressure in the vacuum region and repeating steps a) and b) until a target gas pressure value is achieved;c) measuring a velocity of gas flow along the drift region and repeating steps a) to c) until the measured gas velocity value has achieved a pre-set target gas velocity value and subsequently conducting said differential ion mobility analysis and said mass spectral analysis according to said target gas pressure value and said target gas velocity value.