Tandem Ion Mobility Analyzers for Space Charge Management
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Solution Overview
Problem
Current trapped ion mobility spectrometry (TIMS) analyzers face challenges in precisely analyzing low abundant ions in the presence of high abundant ions due to significant space charge effects, which impairs ion mobility resolution and detection of ion species in complex mixtures.
Innovation Solution
A tandem mass spectrometer configuration with two TIMS analyzers and an ion gate or mass filter is used to selectively separate and transfer ions of interest, adjusting the ion gate's transmission to manage space charge and enhance ion mobility resolution, allowing for precise analysis of low abundant ions by reducing the impact of space charge and improving ion detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high abundant ions are present in the ion mobility analyzer, then the ion signal strength is improved, but the space charge effects increase and impair ion mobility resolution
Solution Approach 1:
The patent divides the ion mobility analysis into two sequential TIMS analyzers. The first TIMS analyzer handles the separation of ions including high abundant ions, while the second TIMS analyzer performs the high-resolution mobility measurement. This segmentation allows the first analyzer to manage space charge from abundant ions without compromising the resolution in the second analyzer, thus resolving the contradiction between signal strength and mobility resolution.
2Measurement precision
If the ion gate transmission is increased to detect low abundant ions, then the detection sensitivity is improved, but the space charge effects from high abundant ions also increase
Solution Approach 1:
The patent uses the ion gate to selectively extract and transmit only ions within a specific mobility range to the second TIMS analyzer. By adjusting the ion gate transmission, low abundant ions can be transmitted for sensitive detection while high abundant ions are blocked or partially transmitted, thereby reducing their space charge influence. This extraction principle allows selective detection of low abundant ions while minimizing harmful space charge effects.
3Measurement precision
If the ion mobility analyzer is designed for high resolution, then the ion mobility resolution is improved, but the device complexity increases
Solution Approach 1:
The patent combines two TIMS analyzers in sequence, where each analyzer is a relatively simple trapped ion mobility spectrometry device. Rather than designing a single complex high-resolution analyzer, the system merges two simpler TIMS units, with the first handling ion separation and the second providing high-resolution measurement. This merging approach achieves high overall resolution while keeping individual device components simpler and more manageable.
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 significantly enhances ion mobility resolution and detection capabilities, enabling the analysis of more ion species with reduced space charge influence, leading to more stable and precise mobility-mass spectra, even with higher ion loads.
Implementation Method 1
A gas flow inside a tube drives ions entrained in the gas flow against a ramped counter-acting electric DC field barrier
Implementation Method 2
the friction force of the moving gas equals the counter-acting force of the electric DC field on the ramp
Implementation Method 3
a radial RF quadrupole field is generated to hold ions near to the axis
Implementation Method 4
separating ions in time according to mobility in the first ion mobility analyzer
Data Source
AI summary
The invention proposes a mass spectrometer comprising two ion mobility analyzers in tandem arrangement, of which at least one is a trapped ion mobility spectrometer (TIMS), and an ion gate which is located between the two ion mobility analyzers, and use thereof wherein ions are selectively transferred between the two ion mobility analyzers by adjusting the transmission of the ion gate while ions are separated in time according to ion mobility in the first ion mobility analyzer.