Parallel RF Ion Trap for Trapping IMS Duty Cycle
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Solution Overview
Problem
The utilization rate of ions produced in an ion source is limited by the duty cycle in existing trapping ion mobility spectrometers, particularly when coupled with electrospray ion sources for analyzing complex samples in bottom-up proteomics, leading to restricted mobility resolution.
Innovation Solution
The implementation of an RF ion trap as an accumulation unit operating in parallel with the trapping ion mobility separator, allowing for continuous ion accumulation and transfer, with adjustable electric field profiles to minimize ion losses and enhance ion storage capacity using quadrupolar, hexapolar, or octopolar RF fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ions are accumulated and separated sequentially in a single trapping ion mobility separator, then mobility resolution is improved, but the duty cycle is limited to below 100%
Solution Approach 1:
The device divides the ion processing function into two separate units: an accumulation unit and a scan unit. The accumulation unit continuously accumulates ions from the ion source, while the scan unit performs the mobility separation and detection. This segmentation allows the accumulation unit to operate continuously at 100% duty cycle while the scan unit maintains high mobility resolution through sequential scanning.
2Measurement precision
If the separator tunnel length is increased to improve mobility resolution, then ion mobility resolution increases, but the device size and complexity increase
Solution Approach 1:
By separating the accumulation function from the scan function into different units, the patent allows the scan unit to maintain a compact separator tunnel design while achieving high mobility resolution through optimized scanning parameters. The accumulation unit handles the time-consuming accumulation process, freeing the scan unit to focus on high-resolution separation with a shorter, simpler tunnel.
3Quantity of substance
If ions are accumulated for longer periods to improve signal intensity, then ion accumulation efficiency improves, but the overall analysis time increases
Solution Approach 1:
The accumulation unit operates continuously to accumulate ions from the ion source, eliminating idle time between accumulation and scanning phases. While the scan unit performs mobility separation, the accumulation unit is already preparing the next batch of ions, ensuring continuous productive operation and maximizing ion utilization without extending overall analysis time.
Solution Approach 2:
Ions are accumulated in advance in the accumulation unit before being transferred to the scan unit for mobility separation. This preliminary accumulation action allows the system to prepare sufficient ion quantities ahead of time, ensuring that the scanning phase can proceed efficiently without waiting for ion accumulation, thereby reducing overall analysis time.
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 enables a near 100% duty cycle and higher mobility resolution by continuously accumulating and analyzing ions, reducing ion losses and improving the efficiency of ion utilization, especially for high mass ions.
Implementation Method 1
The separation of ions according to their mobilities is based upon a gas flow in the cylindrical separator tunnel which drives the ions from an ion source in an accumulation phase against a counter-acting electric DC field barrier while the ions are radially confined by a quadrupolar RF field.
Implementation Method 2
The separation of ions according to their mobilities is based upon a gas flow in the cylindrical separator tunnel which drives the ions from an ion source
Implementation Method 3
a gas flow in the cylindrical separator tunnel which drives the ions from an ion source in an accumulation phase against a counter-acting electric DC field barrier
Data Source
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AI summary
The invention relates to the operation of trapping ion mobility spectrometers based on pushing ions by a gas flow against a counter-acting electric DC field barrier, preferably in combination with a mass analyzer as ion detector. The invention provides a linear RF ion trap upstream of the trapping ion mobility spectrometer, wherein the RF ion trap is operated as an accumulation unit in parallel with the trapping ion mobility spectrometer such that a first group of ions can be analyzed in the trapping ion mobility spectrometer while a second group of ions from an ion source are simultaneously collected in accumulation unit.