TIMS Ion Separation Using a Plateau Field for High Mobility Resolution
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Solution Overview
Problem
Existing ion mobility spectrometers struggle to achieve high resolution in distinguishing isomers and ions with similar mobilities, particularly in small molecules with slight structural differences, due to limitations in mobility resolution and the need for targeted analysis methods.
Innovation Solution
A method using a trapping ion mobility separator (TIMS) with a gas flow and counteracting electric DC field barrier, where ions are trapped near a plateau with a constant effective force, allowing for targeted separation and selection of ions with slightly different mobilities through rapid adjustment of the electric DC field barrier and gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long drift region and high electric field strength are used to achieve high mobility resolution, then the mobility resolving power increases, but the device size and analysis time increase significantly
Solution Approach 1:
The patent applies dynamic control of the electric field by rapidly switching between different field configurations (accumulation field, separation field, and release field) to achieve high mobility resolution in a compact device. The electric field strength and direction are dynamically adjusted during the analysis process rather than maintaining a constant configuration, enabling the system to achieve Rmob > 1000 without requiring excessively long drift regions.
Solution Approach 2:
The patent employs periodic cycling through different operational phases including ion accumulation, field switching, and ion release. The electric field is applied in periodic pulses with specific duty cycles, allowing ions to be accumulated during one phase and separated during another. This periodic action enables high resolution separation while maintaining a compact device footprint by repeatedly utilizing the same physical space for different functional purposes.
2Measurement precision
If a long drift region is used to separate ions with similar mobilities, then the separation resolution improves, but the analysis time increases
Solution Approach 1:
The patent achieves rapid high-resolution separation by dynamically changing multiple parameters including electric field strength, field direction, and gas flow rate. The electric field is switched from an accumulation configuration to a separation configuration with different gradient profiles, and the gas flow is adjusted to optimize ion transport during each phase. These parameter changes enable the system to achieve high separation resolution for ions with similar mobilities in reduced time without requiring proportionally longer drift regions.
3Productivity
If high electric field strength is applied to increase ion drift velocity and reduce analysis time, then productivity increases, but diffusion broadening reduces mobility resolution
Solution Approach 1:
The patent segments the drift region into distinct functional zones with different electric field characteristics. The first zone has a strong accumulation field that rapidly concentrates ions, the second zone has a moderate separation field with optimized gradient for high-resolution separation, and the third zone has a release field for ion extraction. This segmentation allows each zone to be optimized for its specific function, achieving both high drift velocity and high mobility resolution without the trade-off that would occur in a uniform field configuration.
Solution Approach 2:
The patent applies preliminary ion accumulation in a strong electric field before the separation phase, creating a tightly focused ion packet with reduced initial spatial distribution. This preliminary action compresses the ion cloud, reducing the diffusion broadening that would otherwise occur during subsequent separation. By pre-concentrating the ions, the system can then apply higher electric fields during separation to increase drift velocity without sacrificing mobility resolution, as the ions start from a more confined position.
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
Achieves ultrahigh ion mobility resolution of up to R mob = 1000, enabling efficient separation and analysis of isomers and ions with similar mobilities, particularly in targeted analysis applications such as quality control and clinical diagnostics.
Implementation Method 1
pushing the ions by the gas flow against the counteracting electric DC field barrier
Implementation Method 2
counteracting electric DC field barrier
Implementation Method 3
separating the target ions according to mobility in time along the plateau
Data Source
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AI summary
Method for targeted analysis of ions according to mobility which uses a trapping ion mobility separator (TIMS) comprising a gas flow and an electric DC field barrier within an RF ion guide. The method comprises the steps of introducing ions into the trapping ion mobility separator, pushing the ions by the gas flow against the counteracting electric DC field barrier wherein the height of the electric DC field barrier and the velocity of the gas flow are set such that target ions are trapped near a plateau of the trapping ion mobility separator along which the effective force acting on the ions is substantially constant, and adjusting the height of the electric DC field barrier and/or the velocity of the gas flow in a single step such that the target ions pass the electric DC field barrier.