Multi-Reflection TOF Mass Spectrometer Ion Separation
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Solution Overview
Problem
Current MALDI TOF mass spectrometry for bacterial identification has limitations due to low resolution and sensitivity, which can lead to inaccurate identification of microorganisms, and existing high-resolution instruments are either expensive or not suited for large singly charged species.
Innovation Solution
A method utilizing a multi-pass time-of-flight (TOF) mass spectrometer with a bi-directional ion deflector and multi-reflection configuration, allowing ions to travel repeatedly and separate by time of flight, generating fingerprints that can be compared to a library for identification, even without a traditional mass spectrum, and providing higher resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MALDI TOF mass spectrometry is used for bacterial identification, then the technique is relatively rapid and has minimal consumable costs, but the resolution and sensitivity are low leading to inaccurate identification
Solution Approach 1:
The patent transitions from conventional linear TOF path to a multi-dimensional reflected ion path within the mass spectrometer. Ions are reflected multiple times between electrostatic mirrors, effectively extending the flight path length without increasing the physical instrument size. This dimensional transformation enables high-resolution separation of ions with similar m/z ratios while maintaining a compact instrument design suitable for routine bacterial identification.
2Measurement precision
If high-resolution mass spectrometers are used to improve identification accuracy, then resolution and sensitivity increase, but the equipment becomes expensive and large
Solution Approach 1:
The patent uses multiple reflections between electrostatic mirrors to extend the effective ion flight path length by a factor of 10-100 times the physical instrument dimensions. This allows achieving high spectral resolution (R>10,000) typically requiring large instrument footprints, while maintaining a compact design suitable for routine bacterial identification laboratories.
Solution Approach 2:
The patent changes the operational parameters of the TOF mass spectrometer by implementing multi-reflection geometry with electrostatic mirrors. By adjusting the number of reflections and mirror voltages, the system achieves variable resolution modes (R=1,000 to R>10,000) without requiring multiple different instruments, thereby reducing overall system cost and complexity while maintaining high measurement precision.
3Measurement precision
If more peaks are detected in the mass spectrum, then the fingerprint quality improves for accurate identification, but the complexity of data processing and library matching increases
Solution Approach 1:
The patent implements peak filtering based on signal-to-noise ratio thresholds and intensity cutoffs to distinguish true biological peaks from noise. By applying these parameter-based filters, the system reduces the number of peaks requiring processing while preserving the characteristic fingerprint peaks necessary for accurate bacterial identification, thereby balancing fingerprint quality with data processing efficiency.
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 more accurate and confident identification of microorganisms by generating high-resolution fingerprints that can match with reference samples, increasing the mass range and sensitivity, and reducing the need for expensive equipment.
Implementation Method 1
introducing at a time to the sample ions into a sample multi-pass time of flight (TOF) mass spectrometer and causing at least some of the ions to travel repeatedly along a path in the TOF mass spectrometer where ions of different m/z separate in time of flight
Implementation Method 2
ejecting the sample ions from the TOF starting at a time t1 (>t0)
Data Source
AI summary
A multi reflection time of flight (MRTOF) mass spectrometer (12) And method for identifying a sample is disclosed. Sample ions are generated at an ion source (15). The MRTOF is a closed mirror arrangement with first and second opposed ion mirrors (20, 20′) on an axis of reflection (XX′). The MRTOF (12) also includes a bidirectional ion deflector (50) on that axis (XX′). The deflector (50) deflects ions onto the reflection axis as a short pulse at time to <zero> where they oscillate multiple times, separating in time of flight according to ion m/z. At a later time t, ions travelling in both directions along the axis (XX′) are ejected out of the MRTOF (12) by the bidirectional deflector (50) to an ion detector arrangement (55). The separation of ions in time of flight allows a “fingerprint” of a biological sample to be produced by the detector arrangement (55) without the need to assign a mass to each peak. Comparison with a library of fingerprints permits identification.