Ion Filter Combining Mobility Selection and Ion Fragmentation
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Solution Overview
Problem
Current mass spectrometry techniques face challenges in accurately identifying substances of interest, such as explosives and chemical warfare agents, due to the ambiguity of mass-to-charge ratios and the need for reliable ion selection and modification methods.
Innovation Solution
The development of an ion filter system comprising an ion selector and an ion modifier for mass spectrometers, which selects and modifies ions based on their mobility characteristics, allowing for the analysis of both unmodified and modified ions to enhance identification accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass spectrometry is used to identify substances by mass-to-charge ratio, then identification can be performed, but accuracy is reduced because multiple different ion species can have the same mass-to-charge ratio
Solution Approach 1:
The invention segments the ion analysis process into two independent measurement dimensions: mass-to-charge ratio measurement (by the mass spectrometer) and ion mobility measurement (by the ion mobility spectrometer). This segmentation allows each instrument to measure a different property of the same ion population, thereby resolving the ambiguity where multiple species share the same mass-to-charge ratio. The combined data from both measurements provides unique identification for each ion species.
Solution Approach 2:
The invention adds a second measurement dimension (ion mobility) to the traditional single-dimension mass spectrometry approach. By measuring both mass-to-charge ratio and ion mobility, the system transforms the identification problem from a one-dimensional to a two-dimensional space, where each ion species has a unique coordinate pair (m/z, mobility) rather than sharing a single m/z value. This dimensional expansion eliminates the information loss inherent in single-dimension analysis.
2Loss of information
If ion mobility spectrometry is used to separate ions by mobility, then additional identification information is obtained, but device complexity increases due to the need for multiple spectrometers
Solution Approach 1:
The invention merges the ion mobility spectrometer and mass spectrometer into a single integrated system where ions are sequentially analyzed by both instruments. The ion mobility spectrometer first separates and measures ion mobility, then the same ion population is introduced to the mass spectrometer for mass-to-charge ratio measurement. This merging approach obtains comprehensive identification information from both techniques while avoiding the complexity of operating completely separate, independent spectrometer systems.
Solution Approach 2:
The integrated system performs multiple functions using a unified platform: it conducts ion mobility measurement, mass spectrometry measurement, and combined analysis all within one system architecture. This multi-functionality reduces device complexity compared to having separate specialized instruments, as the system is designed to handle both measurement types through a common ion introduction and control framework.
3Reliability
If both unmodified and modified ions are analyzed, then identification reliability is improved through multiple data points, but analysis time increases due to sequential processing
Solution Approach 1:
The system employs periodic action by sequentially alternating between analyzing unmodified ions and modified ions in repeated cycles. Rather than processing all unmodified ions then all modified ions in separate batches, the system performs multiple rapid sequential measurements, alternating between the two ion types. This periodic measurement approach accumulates statistical reliability from multiple data points while minimizing total analysis time through efficient cycling between measurement modes.
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 precise identification of substances by selecting and modifying ions based on mobility, improving the accuracy and reliability of mass spectrometry analysis, particularly for substances like explosives and chemical warfare agents.
Implementation Method 1
The ion selector selects a subset of a sample of ions based on their mobility in a gas
Implementation Method 2
The ion modifier is controlled to modify the subset of ions selected by the ion selector to output daughter ions
Implementation Method 3
Mass spectrometry works by ionizing chemical compounds to generate charged molecules or molecule fragments and measuring their mass-to-charge ratios
Implementation Method 4
Ion mobility spectrometers (IMS) can identify material from a sample of interest by ionizing the material (e.g., molecules, atoms) and measuring the time it takes the resulting ions to travel a known distance under a known electric field
Data Source
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AI summary
An ion filter for a mass spectrometer, the apparatus comprising an ion modifier; an ion selector configured to select a subset of a sample of ions based on their mobility in a gas; and a controller configured to operate the ion modifier in a first mode to modify the ions selected by the ion selector to provide daughter ions, and configured to operate the ion modifier in a second mode to output the ions selected by the ion selector;wherein the ion filter is adapted for providing output ions from the ion modifier to an intake of a mass spectrometer.