Rotating Field Ion Mass Filter
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Solution Overview
Problem
Conventional mass filters, such as quadrupoles and ion traps, face challenges in achieving narrow mass-to-charge ratio isolation windows without significant losses in ion transmission, limiting their ability to improve sensitivity and accuracy in mass spectrometry analyses.
Innovation Solution
The use of a system comprising an accelerator, a deflector, and an aperture to separate and filter ions by applying an acceleration electric field and a rotating or raster-scanned field, allowing for high transmission efficiency while isolating ions within a narrow mass range, typically 100 mDa or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional mass filters (quadrupole or ion trap) are operated at unit resolution to maintain high ion transmission, then ion transmission efficiency is improved (20-50%), but the isolation window remains wide (0.7 Da) limiting mass resolution
Solution Approach 1:
The patent applies a dynamically rotating electric field that continuously changes direction and magnitude to deflect ions onto a circular trajectory. This dynamic field configuration enables precise control of ion paths, allowing narrow mass isolation windows (≤0.1 Da) while maintaining high ion transmission through the aperture at specific phases of the rotating field cycle.
Solution Approach 2:
The system changes the temporal and spatial parameters of the electric field by rotating it at controlled frequencies and amplitudes. By adjusting the rotation speed and field strength, the system can selectively transmit ions with specific mass-to-charge ratios through the aperture while deflecting others, achieving both high resolution and transmission efficiency.
2Measurement precision
If quadrupole mass filter is operated to deliver higher resolution with narrower mass window, then mass resolution is improved, but ion transmission is reduced much faster than linearly with window narrowing
Solution Approach 1:
The patent transitions from the conventional linear transmission path through a quadrupole to a two-dimensional circular trajectory in the deflection plane. Ions are deflected onto a circular path by the rotating electric field, and the aperture samples ions at specific angular positions. This dimensional change allows precise mass selection through angular positioning while maintaining transmission through the aperture.
Solution Approach 2:
The rotating electric field applies periodic deflection forces to ions, creating a continuous circular motion. The aperture is positioned to transmit ions at specific phases of this periodic cycle, enabling selective mass filtering. The periodic nature of the field allows continuous operation with both high resolution and transmission 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 high-resolution mass filtering with up to 100% ion transmission, effectively narrowing the isolation window to achieve precise ion selection and reduce systematic errors in mass spectrometry analyses.
Implementation Method 1
The accelerator receives a continuous beam of ions and applies an acceleration electric field to the continuous beam of ions producing an accelerated beam of ions.
Implementation Method 2
The deflector applies a rotating field to the accelerated beam to separate ions in time and space producing a separated beam of ions.
Data Source
AI summary
Systems and methods for filtering a continuous beam of ions are provided. An acceleration electric field is applied to a continuous beam of ions using an accelerator to produce an accelerated beam of ions. A field is applied to the accelerated beam to separate ions in time and space using a deflector producing a separated beam of ions. The field applied by the deflector is a rotating field or a circulant rastering field. The rotating field can be a rotating magnetic or electric field. Only accept those ions from the separated beam whose m/z values lie within a range centered around a target m/z value using an aperture. The aperture can include a pinhole aperture in a rotating disk or an annular aperture in a first stationary disk, a second deflector, and a pinhole aperture in the center of a second stationary disk.