Helical Trajectory TOF-MS for Mass Resolution
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Solution Overview
Problem
Current time-of-flight (TOF) mass spectrometry systems face limitations in achieving high mass resolution and accuracy due to issues such as limited flight time, interference from fragment ions, and challenges in focusing ions in the orthogonal direction, which affect sensitivity and mass analysis precision.
Innovation Solution
The implementation of a helical-trajectory TOF-MS system with laminated toroidal electric fields, which allows ions to travel in a helical path, increasing flight distance and time, and incorporating a deflector to adjust the ion trajectory, thereby enhancing focusing and reducing interference from fragment ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear TOF-MS is used, then the structure is simple, but the total flight time is limited to tens of microseconds resulting in insufficient mass resolution
Solution Approach 1:
The patent transitions from linear flight path to helical trajectory by adding a third dimension (orthogonal direction), allowing ions to complete multiple revolutions around the axis. This dimensional change increases flight path length and total flight time without proportionally increasing apparatus size, thereby improving mass resolution while maintaining reasonable structural complexity
Solution Approach 2:
The patent employs nested electromagnetic fields where a toroidal electric field is generated within a cylindrical magnetic field. This nested configuration allows the electric field to be contained within the magnetic field structure, enabling the helical trajectory mechanism to achieve extended flight time without requiring a proportionally larger overall apparatus, thus improving mass resolution with controlled device complexity
2Measurement precision
If the total flight time is increased in a linear TOF-MS, then mass resolution improves, but the apparatus size must be increased
Solution Approach 1:
By introducing helical motion through orthogonal electromagnetic fields, the patent enables ions to traverse a longer path length within a compact volume. The helical trajectory packs the flight path into three-dimensional space efficiently, achieving extended total flight time (milliseconds to hundreds of milliseconds) without requiring a linearly proportional increase in apparatus length
Solution Approach 2:
The patent employs curved helical trajectory instead of linear path, allowing ions to revolve around the central axis multiple times. This curvature enables the flight path to be folded back on itself within a compact volume, achieving long flight time without large apparatus dimensions
3Measurement precision
If fragment ions are present during flight, then the mass spectrum becomes complicated, but preventing fragmentation requires controlling ion energy
Solution Approach 1:
The patent utilizes the mass-dependent nature of the helical trajectory parameters (radius, pitch angle) to differentiate precursor ions from fragment ions. By measuring these trajectory parameters, the system can identify and exclude fragment ions from the mass spectrum, achieving spectrum clarity without requiring strict control of ion energy that would prevent fragmentation
4Measurement precision
If multiple deflectors are added to focus ions in the orthogonal direction, then sensitivity improves, but device complexity increases
Solution Approach 1:
The patent employs electromagnetic fields that serve multiple functions simultaneously: the toroidal electric field provides both radial confinement and longitudinal acceleration, while the cylindrical magnetic field provides both helical trajectory formation and orbital confinement. This multi-functionality achieves orthogonal focusing and sensitivity improvement without requiring separate dedicated deflector components for each function
Solution Approach 2:
The patent combines the focusing functions into the primary helical trajectory-generating fields themselves, rather than adding separate focusing components. The same electromagnetic fields that create the helical path also provide the necessary focusing in the orthogonal direction, reducing overall device complexity while maintaining sensitivity
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 configuration improves mass analysis accuracy and sensitivity by increasing flight time and reducing ion interference, allowing for more precise separation and detection of isotope peaks, and enabling high-mass resolution without the need for delayed extraction techniques.
Implementation Method 1
means for accelerating ions in a pulsed manner
Implementation Method 2
a magnetic field, wherein the ions travel in a helical trajectory in the direction of the axis of rotation of the toroidal electric field
Implementation Method 3
a flight time measurement is performed from a moment when the pulsed voltage is applied to a moment when the ions arrive at the ion detector
Data Source
AI summary
A method and apparatus for time-of-flight (TOF) mass spectrometry. The apparatus improves the ion focusing properties in an orthogonal direction and permits connection with an orthogonal-acceleration ion source for improvement of sensitivity. The apparatus comprises an ion source for emitting ions in a pulsed manner, an analyzer for realizing a helical trajectory, and a detector for detecting the ions. The analyzer is composed of plural laminated toroidal electric fields to realize the helical trajectory.